diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -1375,7 +1375,7 @@
 coreconfigitem(
     b'format',
     b'use-share-safe',
-    default=False,
+    default=True,
 )
 coreconfigitem(
     b'format',
diff --git a/mercurial/helptext/config.txt b/mercurial/helptext/config.txt
--- a/mercurial/helptext/config.txt
+++ b/mercurial/helptext/config.txt
@@ -998,7 +998,7 @@
 
     Introduced in Mercurial 5.7.
 
-    Disabled by default.
+    Enabled by default in Mercurial 6.1.
 
 ``usestore``
     Enable or disable the "store" repository format which improves
diff --git a/mercurial/upgrade_utils/actions.py b/mercurial/upgrade_utils/actions.py
--- a/mercurial/upgrade_utils/actions.py
+++ b/mercurial/upgrade_utils/actions.py
@@ -243,7 +243,7 @@
     name = b'share-safe'
     _requirement = requirements.SHARESAFE_REQUIREMENT
 
-    default = False
+    default = True
 
     description = _(
         b'old shared repositories do not share source repository '
diff --git a/relnotes/next b/relnotes/next
--- a/relnotes/next
+++ b/relnotes/next
@@ -4,7 +4,15 @@
 == Default Format Change ==
 
 These changes affects newly created repositories (or new clone) done with
-Mercurial XXX.
+Mercurial 6.1.
+
+The `share-safe` format variant is now enabled by default. It makes
+configuration and repository more consistenty across repository and their
+shares. This introduce a behavior changes as share from repository using the
+new repository will also use their main repository configuration.
+
+See `hg help config.format.use-share-safe` for details about the feature and
+the available options for auto-upgrading existing shares.
 
 
 == New Experimental Features ==
@@ -15,6 +23,9 @@
 
 == Backwards Compatibility Changes ==
 
+The use of `share-safe`, mean shares (of new repositories) will see the
+`Default Format Change` section for details.
+
 
 == Internal API Changes ==
 
diff --git a/tests/test-empty.t b/tests/test-empty.t
--- a/tests/test-empty.t
+++ b/tests/test-empty.t
@@ -25,9 +25,10 @@
   store
   wcache
 
-Should be empty:
+Should be empty (except for the "basic" requires):
 
   $ ls .hg/store
+  requires
 
 Poke at a clone:
 
@@ -51,8 +52,9 @@
   store
   wcache
 
-Should be empty:
+Should be empty (except for the "basic" requires):
 
   $ ls .hg/store
+  requires
 
   $ cd ..
diff --git a/tests/test-fncache.t b/tests/test-fncache.t
--- a/tests/test-fncache.t
+++ b/tests/test-fncache.t
@@ -153,6 +153,7 @@
   .hg/store/data/tst.d.hg
   .hg/store/data/tst.d.hg/_foo.i
   .hg/store/phaseroots
+  .hg/store/requires
   .hg/store/undo
   .hg/store/undo.backupfiles
   .hg/store/undo.phaseroots
diff --git a/tests/test-hardlinks.t b/tests/test-hardlinks.t
--- a/tests/test-hardlinks.t
+++ b/tests/test-hardlinks.t
@@ -52,6 +52,7 @@
   1 r1/.hg/store/data/f1.i
   1 r1/.hg/store/fncache (repofncache !)
   1 r1/.hg/store/phaseroots
+  1 r1/.hg/store/requires
   1 r1/.hg/store/undo
   1 r1/.hg/store/undo.backup.fncache (repofncache !)
   1 r1/.hg/store/undo.backupfiles
@@ -93,6 +94,7 @@
   2 r1/.hg/store/data/f1.i
   1 r1/.hg/store/fncache (repofncache !)
   1 r1/.hg/store/phaseroots
+  1 r1/.hg/store/requires
   1 r1/.hg/store/undo
   1 r1/.hg/store/undo.backup.fncache (repofncache !)
   1 r1/.hg/store/undo.backupfiles
@@ -104,6 +106,7 @@
   2 r2/.hg/store/data/d1/f2.i
   2 r2/.hg/store/data/f1.i
   1 r2/.hg/store/fncache (repofncache !)
+  1 r2/.hg/store/requires
 
 Repo r3 should not be hardlinked:
 
@@ -114,6 +117,7 @@
   1 r3/.hg/store/data/f1.i
   1 r3/.hg/store/fncache (repofncache !)
   1 r3/.hg/store/phaseroots
+  1 r3/.hg/store/requires
   1 r3/.hg/store/undo
   1 r3/.hg/store/undo.backupfiles
   1 r3/.hg/store/undo.phaseroots
@@ -140,6 +144,7 @@
   1 r3/.hg/store/data/f1.i
   1 r3/.hg/store/fncache (repofncache !)
   1 r3/.hg/store/phaseroots
+  1 r3/.hg/store/requires
   1 r3/.hg/store/undo
   1 r3/.hg/store/undo.backup.fncache (repofncache !)
   1 r3/.hg/store/undo.backup.phaseroots
@@ -172,6 +177,7 @@
   1 r2/.hg/store/data/d1/f2.i
   2 r2/.hg/store/data/f1.i
   [12] r2/\.hg/store/fncache (re) (repofncache !)
+  1 r2/.hg/store/requires
 
 #if hardlink-whitelisted repofncache
   $ nlinksdir r2/.hg/store/fncache
@@ -202,6 +208,7 @@
   1 r2/.hg/store/data/d1/f2.i
   1 r2/.hg/store/data/f1.i
   1 r2/.hg/store/fncache (repofncache !)
+  1 r2/.hg/store/requires
 
 #if hardlink-whitelisted repofncache
   $ nlinksdir r2/.hg/store/fncache
@@ -261,6 +268,7 @@
   2 r4/.hg/store/data/f3.i
   2 r4/.hg/store/fncache (repofncache !)
   2 r4/.hg/store/phaseroots
+  2 r4/.hg/store/requires
   2 r4/.hg/store/undo
   2 r4/.hg/store/undo.backup.fncache (repofncache !)
   2 r4/.hg/store/undo.backup.phaseroots
@@ -318,6 +326,7 @@
   2 r4/.hg/store/data/f3.i
   2 r4/.hg/store/fncache
   2 r4/.hg/store/phaseroots
+  2 r4/.hg/store/requires
   2 r4/.hg/store/undo
   2 r4/.hg/store/undo.backup.fncache (repofncache !)
   2 r4/.hg/store/undo.backup.phaseroots
diff --git a/tests/test-hook.t b/tests/test-hook.t
--- a/tests/test-hook.t
+++ b/tests/test-hook.t
@@ -464,6 +464,7 @@
   fncache (repofncache !)
   journal.phaseroots
   phaseroots
+  requires
   undo
   undo.backup.fncache (repofncache !)
   undo.backupfiles
diff --git a/tests/test-inherit-mode.t b/tests/test-inherit-mode.t
--- a/tests/test-inherit-mode.t
+++ b/tests/test-inherit-mode.t
@@ -54,6 +54,7 @@
   00770 ./.hg/cache/
   00600 ./.hg/requires
   00770 ./.hg/store/
+  00600 ./.hg/store/requires
   00770 ./.hg/wcache/
 
   $ mkdir dir
@@ -92,6 +93,7 @@
   00660 ./.hg/store/data/foo/index (reposimplestore !)
   00660 ./.hg/store/fncache (repofncache !)
   00660 ./.hg/store/phaseroots
+  00600 ./.hg/store/requires
   00660 ./.hg/store/undo
   00660 ./.hg/store/undo.backupfiles
   00660 ./.hg/store/undo.phaseroots
@@ -121,6 +123,7 @@
   00770 ../push/.hg/cache/
   00660 ../push/.hg/requires
   00770 ../push/.hg/store/
+  00660 ../push/.hg/store/requires
   00770 ../push/.hg/wcache/
 
   $ umask 077
@@ -152,6 +155,7 @@
   00660 ../push/.hg/store/data/foo/b80de5d138758541c5f05265ad144ab9fa86d1db (reposimplestore !)
   00660 ../push/.hg/store/data/foo/index (reposimplestore !)
   00660 ../push/.hg/store/fncache (repofncache !)
+  00660 ../push/.hg/store/requires
   00660 ../push/.hg/store/undo
   00660 ../push/.hg/store/undo.backupfiles
   00660 ../push/.hg/store/undo.phaseroots
diff --git a/tests/test-init.t b/tests/test-init.t
--- a/tests/test-init.t
+++ b/tests/test-init.t
@@ -25,6 +25,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -80,6 +81,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -96,6 +98,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -112,6 +115,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   store
   testonly-simplestore (reposimplestore !)
 
@@ -232,6 +236,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -255,6 +260,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -274,6 +280,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
diff --git a/tests/test-lfconvert.t b/tests/test-lfconvert.t
--- a/tests/test-lfconvert.t
+++ b/tests/test-lfconvert.t
@@ -103,6 +103,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
diff --git a/tests/test-narrow-clone-no-ellipsis.t b/tests/test-narrow-clone-no-ellipsis.t
--- a/tests/test-narrow-clone-no-ellipsis.t
+++ b/tests/test-narrow-clone-no-ellipsis.t
@@ -30,6 +30,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
diff --git a/tests/test-narrow-clone-stream.t b/tests/test-narrow-clone-stream.t
--- a/tests/test-narrow-clone-stream.t
+++ b/tests/test-narrow-clone-stream.t
@@ -72,6 +72,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   treemanifest (tree !)
@@ -86,6 +87,7 @@
   fncache (flat-fncache !)
   meta (tree !)
   narrowspec
+  requires
   undo
   undo.backupfiles
   undo.narrowspec
diff --git a/tests/test-narrow-clone.t b/tests/test-narrow-clone.t
--- a/tests/test-narrow-clone.t
+++ b/tests/test-narrow-clone.t
@@ -46,6 +46,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
diff --git a/tests/test-narrow-sparse.t b/tests/test-narrow-sparse.t
--- a/tests/test-narrow-sparse.t
+++ b/tests/test-narrow-sparse.t
@@ -65,6 +65,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   treemanifest (tree !)
diff --git a/tests/test-persistent-nodemap.t b/tests/test-persistent-nodemap.t
--- a/tests/test-persistent-nodemap.t
+++ b/tests/test-persistent-nodemap.t
@@ -784,7 +784,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:         yes    yes      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap: yes     no      no
   copies-sdc:          no     no      no
@@ -828,7 +828,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:         yes    yes      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no    yes      no
   copies-sdc:          no     no      no
diff --git a/tests/test-remotefilelog-clone-tree.t b/tests/test-remotefilelog-clone-tree.t
--- a/tests/test-remotefilelog-clone-tree.t
+++ b/tests/test-remotefilelog-clone-tree.t
@@ -34,6 +34,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   treemanifest
@@ -78,6 +79,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   treemanifest
@@ -122,6 +124,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   treemanifest
diff --git a/tests/test-remotefilelog-clone.t b/tests/test-remotefilelog-clone.t
--- a/tests/test-remotefilelog-clone.t
+++ b/tests/test-remotefilelog-clone.t
@@ -31,6 +31,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -68,6 +69,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   $ ls .hg/store/data
@@ -120,5 +122,6 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
diff --git a/tests/test-remotefilelog-log.t b/tests/test-remotefilelog-log.t
--- a/tests/test-remotefilelog-log.t
+++ b/tests/test-remotefilelog-log.t
@@ -34,6 +34,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
diff --git a/tests/test-requires.t b/tests/test-requires.t
--- a/tests/test-requires.t
+++ b/tests/test-requires.t
@@ -57,6 +57,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   $ hg -R supported status
diff --git a/tests/test-rhg.t b/tests/test-rhg.t
--- a/tests/test-rhg.t
+++ b/tests/test-rhg.t
@@ -243,6 +243,7 @@
   persistent-nodemap
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
diff --git a/tests/test-sparse-requirement.t b/tests/test-sparse-requirement.t
--- a/tests/test-sparse-requirement.t
+++ b/tests/test-sparse-requirement.t
@@ -24,6 +24,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -45,6 +46,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
@@ -67,6 +69,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   testonly-simplestore (reposimplestore !)
diff --git a/tests/test-sqlitestore.t b/tests/test-sqlitestore.t
--- a/tests/test-sqlitestore.t
+++ b/tests/test-sqlitestore.t
@@ -21,6 +21,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -38,6 +39,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -59,6 +61,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -75,6 +78,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
diff --git a/tests/test-static-http.t b/tests/test-static-http.t
--- a/tests/test-static-http.t
+++ b/tests/test-static-http.t
@@ -240,6 +240,7 @@
   /.hg/store/data/a.i
   /.hg/store/data/~2ehgsub.i (py37 !)
   /.hg/store/data/~2ehgsubstate.i (py37 !)
+  /.hg/store/requires
   /notarepo/.hg/00changelog.i
   /notarepo/.hg/requires
   /remote-with-names/.hg/bookmarks
@@ -255,6 +256,7 @@
   /remote-with-names/.hg/store/data/%7E2ehgtags.i (no-py37 !)
   /remote-with-names/.hg/store/data/foo.i
   /remote-with-names/.hg/store/data/~2ehgtags.i (py37 !)
+  /remote-with-names/.hg/store/requires
   /remote/.hg/bookmarks
   /remote/.hg/bookmarks.current
   /remote/.hg/cache/branch2-base
@@ -274,12 +276,14 @@
   /remote/.hg/store/data/quux.i
   /remote/.hg/store/data/~2edotfile%20with%20spaces.i (py37 !)
   /remote/.hg/store/data/~2ehgtags.i (py37 !)
+  /remote/.hg/store/requires
   /remotempty/.hg/bookmarks
   /remotempty/.hg/bookmarks.current
   /remotempty/.hg/dirstate
   /remotempty/.hg/requires
   /remotempty/.hg/store/00changelog.i
   /remotempty/.hg/store/00manifest.i
+  /remotempty/.hg/store/requires
   /sub/.hg/bookmarks
   /sub/.hg/bookmarks.current
   /sub/.hg/cache/hgtagsfnodes1
@@ -290,3 +294,4 @@
   /sub/.hg/store/data/%7E2ehgtags.i (no-py37 !)
   /sub/.hg/store/data/test.i
   /sub/.hg/store/data/~2ehgtags.i (py37 !)
+  /sub/.hg/store/requires
diff --git a/tests/test-upgrade-repo.t b/tests/test-upgrade-repo.t
--- a/tests/test-upgrade-repo.t
+++ b/tests/test-upgrade-repo.t
@@ -60,7 +60,7 @@
   dirstate-v2:         no
   dotencode:          yes
   generaldelta:       yes
-  share-safe:          no
+  share-safe:         yes
   sparserevlog:       yes
   persistent-nodemap:  no (no-rust !)
   persistent-nodemap: yes (rust !)
@@ -76,7 +76,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -93,7 +93,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes     no     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -110,7 +110,7 @@
   [formatvariant.name.uptodate|dirstate-v2:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.mismatchconfig|dotencode:         ][formatvariant.repo.mismatchconfig| yes][formatvariant.config.special|     no][formatvariant.default|     yes]
   [formatvariant.name.uptodate|generaldelta:      ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
-  [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
+  [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.uptodate|sparserevlog:      ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.uptodate|persistent-nodemap:][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no] (no-rust !)
   [formatvariant.name.mismatchdefault|persistent-nodemap:][formatvariant.repo.mismatchdefault| yes][formatvariant.config.special|    yes][formatvariant.default|      no] (rust !)
@@ -148,10 +148,10 @@
     "repo": true
    },
    {
-    "config": false,
-    "default": false,
+    "config": true,
+    "default": true,
     "name": "share-safe",
-    "repo": false
+    "repo": true
    },
    {
     "config": true,
@@ -210,8 +210,8 @@
   performing an upgrade with "--run" will make the following changes:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   no revlogs to process
   
@@ -232,8 +232,8 @@
 
   $ hg debugupgraderepo --quiet
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   no revlogs to process
   
@@ -245,8 +245,8 @@
   performing an upgrade with "--run" will make the following changes:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -277,8 +277,8 @@
   performing an upgrade with "--run" will make the following changes:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -303,8 +303,8 @@
   
   $ hg debugupgrade --optimize re-delta-parent --quiet
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -349,7 +349,7 @@
   dirstate-v2:         no     no      no
   dotencode:           no    yes     yes
   generaldelta:        no    yes     yes
-  share-safe:          no     no      no
+  share-safe:          no    yes     yes
   sparserevlog:        no    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap:  no    yes      no (rust !)
@@ -366,7 +366,7 @@
   dirstate-v2:         no     no      no
   dotencode:           no    yes     yes
   generaldelta:        no     no     yes
-  share-safe:          no     no      no
+  share-safe:          no    yes     yes
   sparserevlog:        no     no     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap:  no    yes      no (rust !)
@@ -383,7 +383,7 @@
   [formatvariant.name.uptodate|dirstate-v2:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.mismatchconfig|dotencode:         ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.mismatchdefault|generaldelta:      ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]
-  [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
+  [formatvariant.name.mismatchconfig|share-safe:        ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.mismatchdefault|sparserevlog:      ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]
   [formatvariant.name.uptodate|persistent-nodemap:][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no] (no-rust !)
   [formatvariant.name.mismatchconfig|persistent-nodemap:][formatvariant.repo.mismatchconfig|  no][formatvariant.config.special|    yes][formatvariant.default|      no] (rust !)
@@ -410,6 +410,9 @@
   generaldelta
      deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
   
+  share-safe
+     old shared repositories do not share source repository requirements and config. This leads to various problems when the source repository format is upgraded or some new extensions are enabled.
+  
   sparserevlog
      in order to limit disk reading and memory usage on older version, the span of a delta chain from its root to its end is limited, whatever the relevant data in this span. This can severly limit Mercurial ability to build good chain of delta resulting is much more storage space being taken and limit reusability of on disk delta during exchange.
   
@@ -421,8 +424,8 @@
   
   requirements
      preserved: revlogv1, store
-     added: dotencode, fncache, generaldelta, sparserevlog (no-rust !)
-     added: dotencode, fncache, generaldelta, persistent-nodemap, sparserevlog (rust !)
+     added: dotencode, fncache, generaldelta, share-safe, sparserevlog (no-rust !)
+     added: dotencode, fncache, generaldelta, persistent-nodemap, share-safe, sparserevlog (rust !)
   
   fncache
      repository will be more resilient to storing certain paths and performance of certain operations should be improved
@@ -433,6 +436,9 @@
   generaldelta
      repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
   
+  share-safe
+     Upgrades a repository to share-safe format so that future shares of this repository share its requirements and configs.
+  
   sparserevlog
      Revlog supports delta chain with more unused data between payload. These gaps will be skipped at read time. This allows for better delta chains, making a better compression and faster exchange with server.
   
@@ -461,8 +467,8 @@
   $ hg debugupgraderepo --quiet
   requirements
      preserved: revlogv1, store
-     added: dotencode, fncache, generaldelta, sparserevlog (no-rust !)
-     added: dotencode, fncache, generaldelta, persistent-nodemap, sparserevlog (rust !)
+     added: dotencode, fncache, generaldelta, share-safe, sparserevlog (no-rust !)
+     added: dotencode, fncache, generaldelta, persistent-nodemap, share-safe, sparserevlog (rust !)
   
   processed revlogs:
     - all-filelogs
@@ -483,6 +489,9 @@
   generaldelta
      deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
   
+  share-safe
+     old shared repositories do not share source repository requirements and config. This leads to various problems when the source repository format is upgraded or some new extensions are enabled.
+  
   sparserevlog
      in order to limit disk reading and memory usage on older version, the span of a delta chain from its root to its end is limited, whatever the relevant data in this span. This can severly limit Mercurial ability to build good chain of delta resulting is much more storage space being taken and limit reusability of on disk delta during exchange.
   
@@ -499,8 +508,8 @@
   
   requirements
      preserved: revlogv1, store
-     added: fncache, generaldelta, sparserevlog (no-rust !)
-     added: fncache, generaldelta, persistent-nodemap, sparserevlog (rust !)
+     added: fncache, generaldelta, share-safe, sparserevlog (no-rust !)
+     added: fncache, generaldelta, persistent-nodemap, share-safe, sparserevlog (rust !)
   
   fncache
      repository will be more resilient to storing certain paths and performance of certain operations should be improved
@@ -508,6 +517,9 @@
   generaldelta
      repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
   
+  share-safe
+     Upgrades a repository to share-safe format so that future shares of this repository share its requirements and configs.
+  
   sparserevlog
      Revlog supports delta chain with more unused data between payload. These gaps will be skipped at read time. This allows for better delta chains, making a better compression and faster exchange with server.
   
@@ -576,8 +588,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, persistent-nodemap, revlogv1, share-safe, store (rust !)
      added: generaldelta
   
   generaldelta
@@ -602,6 +614,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: -17 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -616,11 +629,14 @@
 Original requirements backed up
 
   $ cat .hg/upgradebackup.*/requires
+  share-safe
+  $ cat .hg/upgradebackup.*/store/requires
   dotencode
   fncache
   persistent-nodemap (rust !)
   revlogv1
   store
+  upgradeinprogress
 
 generaldelta added to original requirements files
 
@@ -630,6 +646,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   store
 
 store directory has files we expect
@@ -640,6 +657,7 @@
   data
   fncache
   phaseroots
+  requires
   undo
   undo.backupfiles
   undo.phaseroots
@@ -668,6 +686,7 @@
   data
   fncache
   phaseroots
+  requires
   undo
   undo.backup.fncache
   undo.backupfiles
@@ -684,8 +703,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      added: sparserevlog
   
   sparserevlog
@@ -710,6 +729,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -726,8 +746,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -756,6 +776,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -804,8 +825,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -835,6 +856,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -855,8 +877,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -885,6 +907,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -905,8 +928,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-parent
   
@@ -935,6 +958,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -958,8 +982,8 @@
   warning: ignoring  --no-manifest, as upgrade is changing: sparserevlog
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      removed: sparserevlog
   
   optimisations: re-delta-parent
@@ -976,8 +1000,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      removed: sparserevlog
   
   optimisations: re-delta-parent
@@ -1009,6 +1033,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -1033,8 +1058,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      added: sparserevlog
   
   optimisations: re-delta-parent
@@ -1069,6 +1094,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: 0 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -1099,8 +1125,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-fulladd
   
@@ -1127,6 +1153,7 @@
   finished migrating 3 total revisions; total change in store size: 0 bytes
   copying .XX_special_filename
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -1165,6 +1192,7 @@
   largefiles
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1177,6 +1205,7 @@
   largefiles
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1265,8 +1294,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
   
   optimisations: re-delta-all
   
@@ -1292,6 +1321,7 @@
   finished migrating 3 changelog revisions; change in size: 0 bytes
   finished migrating 9 total revisions; total change in store size: -9 bytes
   copying phaseroots
+  copying requires
   data fully upgraded in a temporary repository
   marking source repository as being upgraded; clients will be unable to read from repository
   starting in-place swap of repository data
@@ -1328,6 +1358,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   store
 
 Check that we can add the sparse-revlog format requirement
@@ -1335,8 +1366,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      added: sparserevlog
   
   processed revlogs:
@@ -1350,6 +1381,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1358,8 +1390,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      removed: sparserevlog
   
   processed revlogs:
@@ -1373,6 +1405,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   store
 
 #if zstd
@@ -1386,8 +1419,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, store (rust !)
      added: revlog-compression-zstd, sparserevlog
   
   processed revlogs:
@@ -1401,7 +1434,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1419,6 +1452,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1428,8 +1462,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
      removed: revlog-compression-zstd
   
   processed revlogs:
@@ -1443,7 +1477,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1460,6 +1494,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1473,8 +1508,8 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, revlogv1, sparserevlog, store (no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, revlogv1, share-safe, sparserevlog, store (no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlogv1, share-safe, sparserevlog, store (rust !)
      added: revlog-compression-zstd
   
   processed revlogs:
@@ -1488,7 +1523,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1506,6 +1541,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd
   revlogv1
+  share-safe
   sparserevlog
   store
 
@@ -1521,9 +1557,9 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, store (no-zstd !)
-     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, share-safe, store (no-zstd !)
+     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, share-safe, sparserevlog, store (zstd no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, share-safe, sparserevlog, store (rust !)
      removed: revlogv1
      added: exp-revlogv2.2 (zstd !)
      added: exp-revlogv2.2, sparserevlog (no-zstd !)
@@ -1539,7 +1575,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1557,6 +1593,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
+  share-safe
   sparserevlog
   store
   $ hg debugsidedata -c 0
@@ -1570,9 +1607,9 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, sparserevlog, store (no-zstd !)
-     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, share-safe, sparserevlog, store (no-zstd !)
+     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, share-safe, sparserevlog, store (zstd no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, share-safe, sparserevlog, store (rust !)
      removed: exp-revlogv2.2
      added: revlogv1
   
@@ -1587,7 +1624,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1605,6 +1642,7 @@
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
   revlogv1
+  share-safe
   sparserevlog
   store
   $ hg debugsidedata -c 0
@@ -1619,9 +1657,9 @@
   upgrade will perform the following actions:
   
   requirements
-     preserved: dotencode, fncache, generaldelta, sparserevlog, store (no-zstd !)
-     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, sparserevlog, store (zstd no-rust !)
-     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store (rust !)
+     preserved: dotencode, fncache, generaldelta, share-safe, sparserevlog, store (no-zstd !)
+     preserved: dotencode, fncache, generaldelta, revlog-compression-zstd, share-safe, sparserevlog, store (zstd no-rust !)
+     preserved: dotencode, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, share-safe, sparserevlog, store (rust !)
      removed: revlogv1
      added: exp-revlogv2.2
   
@@ -1636,7 +1674,7 @@
   dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
-  share-safe:          no     no      no
+  share-safe:         yes    yes     yes
   sparserevlog:       yes    yes     yes
   persistent-nodemap:  no     no      no (no-rust !)
   persistent-nodemap: yes    yes      no (rust !)
@@ -1654,6 +1692,7 @@
   generaldelta
   persistent-nodemap (rust !)
   revlog-compression-zstd (zstd !)
+  share-safe
   sparserevlog
   store
   $ hg debugsidedata -c 0