diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1659,7 +1659,8 @@
             for n in sorted(closed):
                 yield n
 
-    bundler.newpart('cache:rev-branch-cache', data=generate())
+    bundler.newpart('cache:rev-branch-cache', data=generate(),
+                    mandatory=False)
 
 def _formatrequirementsspec(requirements):
     return urlreq.quote(','.join(sorted(requirements)))
diff --git a/tests/test-bundle-phases.t b/tests/test-bundle-phases.t
--- a/tests/test-bundle-phases.t
+++ b/tests/test-bundle-phases.t
@@ -42,7 +42,7 @@
       26805aba1e600a82e93661149f2313866a221a7b
       f585351a92f85104bff7c284233c338b10eb1df7
       9bc730a19041f9ec7cb33c626e811aa233efb18c
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       26805aba1e600a82e93661149f2313866a221a7b draft
   $ hg strip --no-backup C
@@ -234,7 +234,7 @@
       dc0947a82db884575bb76ea10ac97b08536bfa03
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
       03ca77807e919db8807c3749086dc36fb478cac0
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       dc0947a82db884575bb76ea10ac97b08536bfa03 public
       03ca77807e919db8807c3749086dc36fb478cac0 draft
@@ -260,7 +260,7 @@
   changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
       112478962961147124edd43549aedd1a335e44bf
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
   $ rm bundle
 
@@ -272,7 +272,7 @@
       112478962961147124edd43549aedd1a335e44bf
       dc0947a82db884575bb76ea10ac97b08536bfa03
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       dc0947a82db884575bb76ea10ac97b08536bfa03 public
   $ rm bundle
@@ -284,7 +284,7 @@
   changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
       03ca77807e919db8807c3749086dc36fb478cac0
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       03ca77807e919db8807c3749086dc36fb478cac0 draft
   $ rm bundle
diff --git a/tests/test-bundle-type.t b/tests/test-bundle-type.t
--- a/tests/test-bundle-type.t
+++ b/tests/test-bundle-type.t
@@ -68,7 +68,7 @@
   Stream params: {}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   none-v2
   
   % test bundle type bzip2
@@ -78,7 +78,7 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   bzip2-v2
   
   % test bundle type gzip
@@ -88,7 +88,7 @@
   Stream params: {Compression: GZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   gzip-v2
   
   % test bundle type none-v2
@@ -98,7 +98,7 @@
   Stream params: {}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   none-v2
   
   % test bundle type v2
@@ -108,7 +108,7 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   bzip2-v2
   
   % test bundle type v1
@@ -173,7 +173,7 @@
   Stream params: {Compression: ZS}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   zstd-v2
   
   % test bundle type zstd-v2
@@ -183,7 +183,7 @@
   Stream params: {Compression: ZS}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       c35a0f9217e65d1fdb90c936ffa7dbe679f83ddf
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   zstd-v2
   
 
diff --git a/tests/test-bundle.t b/tests/test-bundle.t
--- a/tests/test-bundle.t
+++ b/tests/test-bundle.t
@@ -803,7 +803,7 @@
   bundling: b 1/3 files (33.33%)
   bundling: b1 2/3 files (66.67%)
   bundling: x 3/3 files (100.00%)
-  bundle2-output-part: "cache:rev-branch-cache" streamed payload
+  bundle2-output-part: "cache:rev-branch-cache" (advisory) streamed payload
 
 #if repobundlerepo
 == Test for issue3441
diff --git a/tests/test-clonebundles.t b/tests/test-clonebundles.t
--- a/tests/test-clonebundles.t
+++ b/tests/test-clonebundles.t
@@ -186,10 +186,10 @@
   0150: 88 75 34 36 75 04 82 55 17 14 36 a4 38 10 04 d8 |.u46u..U..6.8...|
   0160: 21 01 9a b1 83 f7 e9 45 8b d2 56 c7 a3 1f 82 52 |!......E..V....R|
   0170: d7 8a 78 ed fc d5 76 f1 36 25 81 89 c7 ad ec 90 |..x...v.6%......|
-  0180: 54 47 75 2b 89 48 b1 b2 62 ce 8e ce 1e ae 56 41 |TGu+.H..b.....VA|
-  0190: ae 61 ba 4e 41 8e 7e ce 1e ba 60 01 a0 14 23 58 |.a.NA.~...`...#X|
+  0180: 54 47 75 2b 89 48 b1 b2 62 c9 89 c9 19 a9 56 45 |TGu+.H..b.....VE|
+  0190: a9 65 ba 49 45 89 79 c9 19 ba 60 01 a0 14 23 58 |.e.IE.y...`...#X|
   01a0: 81 35 c8 7d 40 cc 04 e2 a4 a4 a6 25 96 e6 94 60 |.5.}@......%...`|
-  01b0: 33 17 5f 54 00 00 01 1b 0a ec                   |3._T......|
+  01b0: 33 17 5f 54 00 00 d3 1b 0d 4c                   |3._T.....L|
 
   $ echo "http://localhost:$HGPORT1/full.hg" > server/.hg/clonebundles.manifest
   $ hg clone -U http://localhost:$HGPORT full-bundle
@@ -530,14 +530,14 @@
   $ cat hg.pid >> $DAEMON_PIDS
 
   $ hg -R server debuglfput gz-a.hg
-  14ee2f0b3f1d14aeeb2fe037e09fc295c3cf59f5
+  1f74b3d08286b9b3a16fb3fa185dd29219cbc6ae
 
   $ cat > server/.hg/clonebundles.manifest << EOF
-  > largefile://14ee2f0b3f1d14aeeb2fe037e09fc295c3cf59f5 BUNDLESPEC=gzip-v2
+  > largefile://1f74b3d08286b9b3a16fb3fa185dd29219cbc6ae BUNDLESPEC=gzip-v2
   > EOF
 
   $ hg clone -U http://localhost:$HGPORT largefile-provided --traceback
-  applying clone bundle from largefile://14ee2f0b3f1d14aeeb2fe037e09fc295c3cf59f5
+  applying clone bundle from largefile://1f74b3d08286b9b3a16fb3fa185dd29219cbc6ae
   adding changesets
   adding manifests
   adding file changes
diff --git a/tests/test-debugbundle.t b/tests/test-debugbundle.t
--- a/tests/test-debugbundle.t
+++ b/tests/test-debugbundle.t
@@ -34,14 +34,14 @@
   changegroup -- {nbchanges: 2, version: 02} (mandatory: True)
       0e067c57feba1a5694ca4844f05588bb1bf82342
       991a3460af53952d10ec8a295d3d2cc2e5fa9690
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
 
 Quiet output
 
   $ hg debugbundle --quiet bundle2.hg
   Stream params: {}
   changegroup -- {nbchanges: 2, version: 02} (mandatory: True)
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
 
 Verbose output:
 
@@ -80,6 +80,6 @@
   
       c
       b80de5d138758541c5f05265ad144ab9fa86d1db 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 0000000000000000000000000000000000000000 0
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
 
   $ cd ..
diff --git a/tests/test-generaldelta.t b/tests/test-generaldelta.t
--- a/tests/test-generaldelta.t
+++ b/tests/test-generaldelta.t
@@ -161,7 +161,7 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       1c5d4dc9a8b8d6e1750966d343e94db665e7a1e9
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       1c5d4dc9a8b8d6e1750966d343e94db665e7a1e9 draft
 
diff --git a/tests/test-http-bad-server.t b/tests/test-http-bad-server.t
--- a/tests/test-http-bad-server.t
+++ b/tests/test-http-bad-server.t
@@ -857,7 +857,7 @@
   write(41 from 41) -> (125) 23\\r\\n\x08LISTKEYS\x00\x00\x00\x02\x01\x00		namespacebookmarks\\r\\n (esc)
   write(9 from 9) -> (116) 4\\r\\n\x00\x00\x00\x00\\r\\n (esc)
   write(9 from 9) -> (107) 4\\r\\n\x00\x00\x00\x1d\\r\\n (esc)
-  write(35 from 35) -> (72) 1d\\r\\n\x16CACHE:REV-BRANCH-CACHE\x00\x00\x00\x03\x00\x00\\r\\n (esc)
+  write(35 from 35) -> (72) 1d\\r\\n\x16cache:rev-branch-cache\x00\x00\x00\x03\x00\x00\\r\\n (esc)
   write(9 from 9) -> (63) 4\\r\\n\x00\x00\x00'\\r\\n (esc)
   write(45 from 45) -> (18) 27\\r\\n\x00\x00\x00\x07\x00\x00\x00\x01\x00\x00\x00\x00default\x96\xee\x1dsT\xc4\xadsr\x04vr\xc3j\x1fV\x1e:jL\\r\\n (esc)
   write(9 from 9) -> (9) 4\\r\\n\x00\x00\x00\x00\\r\\n (esc)
@@ -901,7 +901,7 @@
   write(41 from 41) -> (128) 23\\r\\n\x08LISTKEYS\x00\x00\x00\x02\x01\x00		namespacebookmarks\\r\\n (esc)
   write(9 from 9) -> (119) 4\\r\\n\x00\x00\x00\x00\\r\\n (esc)
   write(9 from 9) -> (110) 4\\r\\n\x00\x00\x00\x1d\\r\\n (esc)
-  write(35 from 35) -> (75) 1d\\r\\n\x16CACHE:REV-BRANCH-CACHE\x00\x00\x00\x03\x00\x00\\r\\n (esc)
+  write(35 from 35) -> (75) 1d\\r\\n\x16cache:rev-branch-cache\x00\x00\x00\x03\x00\x00\\r\\n (esc)
   write(9 from 9) -> (66) 4\\r\\n\x00\x00\x00'\\r\\n (esc)
   write(45 from 45) -> (21) 27\\r\\n\x00\x00\x00\x07\x00\x00\x00\x01\x00\x00\x00\x00default\x96\xee\x1dsT\xc4\xadsr\x04vr\xc3j\x1fV\x1e:jL\\r\\n (esc)
   write(9 from 9) -> (12) 4\\r\\n\x00\x00\x00\x00\\r\\n (esc)
diff --git a/tests/test-lfs-serve-access.t b/tests/test-lfs-serve-access.t
--- a/tests/test-lfs-serve-access.t
+++ b/tests/test-lfs-serve-access.t
@@ -93,7 +93,7 @@
   bundle2-input-part: "listkeys" (params: 1 mandatory) supported
   bundle2-input-part: "phase-heads" supported
   bundle2-input-part: total payload size 24
-  bundle2-input-part: "cache:rev-branch-cache" supported
+  bundle2-input-part: "cache:rev-branch-cache" (advisory) supported
   bundle2-input-part: total payload size 39
   bundle2-input-bundle: 3 parts total
   checking for updated bookmarks
diff --git a/tests/test-obsolete-changeset-exchange.t b/tests/test-obsolete-changeset-exchange.t
--- a/tests/test-obsolete-changeset-exchange.t
+++ b/tests/test-obsolete-changeset-exchange.t
@@ -95,12 +95,12 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   $ hg debugbundle ../f89bcc95eba5-obs.hg
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   obsmarkers -- {} (mandatory: True)
       version: 1 (70 bytes)
       9d73aac1b2ed7d53835eaeec212ed41ea47da53a f89bcc95eba5174b1ccc3e33a82e84c96e8338ee 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
@@ -159,7 +159,7 @@
   bundle2-output-part: "changegroup" (params: 1 mandatory 1 advisory) streamed payload
   bundle2-output-part: "listkeys" (params: 1 mandatory) empty payload
   bundle2-output-part: "phase-heads" 24 bytes payload
-  bundle2-output-part: "cache:rev-branch-cache" streamed payload
+  bundle2-output-part: "cache:rev-branch-cache" (advisory) streamed payload
   bundle2-input-bundle: with-transaction
   bundle2-input-part: "changegroup" (params: 1 mandatory 1 advisory) supported
   adding changesets
@@ -172,7 +172,7 @@
   bundle2-input-part: "listkeys" (params: 1 mandatory) supported
   bundle2-input-part: "phase-heads" supported
   bundle2-input-part: total payload size 24
-  bundle2-input-part: "cache:rev-branch-cache" supported
+  bundle2-input-part: "cache:rev-branch-cache" (advisory) supported
   bundle2-input-part: total payload size 39
   bundle2-input-bundle: 3 parts total
   checking for updated bookmarks
diff --git a/tests/test-obsolete.t b/tests/test-obsolete.t
--- a/tests/test-obsolete.t
+++ b/tests/test-obsolete.t
@@ -1454,7 +1454,7 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       e008cf2834908e5d6b0f792a9d4b0e2272260fb8
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       e008cf2834908e5d6b0f792a9d4b0e2272260fb8 draft
 
@@ -1498,7 +1498,7 @@
   changegroup -- {nbchanges: 2, version: 02} (mandatory: True)
       e016b03fd86fcccc54817d120b90b751aaf367d6
       b0551702f918510f01ae838ab03a463054c67b46
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   obsmarkers -- {} (mandatory: True)
       version: 1 (92 bytes)
       e008cf2834908e5d6b0f792a9d4b0e2272260fb8 b0551702f918510f01ae838ab03a463054c67b46 0 (Thu Jan 01 00:00:00 1970 +0000) {'ef1': '8', 'operation': 'amend', 'user': 'test'}
diff --git a/tests/test-patchbomb.t b/tests/test-patchbomb.t
--- a/tests/test-patchbomb.t
+++ b/tests/test-patchbomb.t
@@ -388,15 +388,15 @@
   Content-Disposition: attachment; filename="bundle.hg"
   Content-Transfer-Encoding: base64
   
-  SEcyMAAAAA5Db21wcmVzc2lvbj1CWkJaaDkxQVkmU1kHdO0GAAAN////vFcSXL9/8H7R09C/578I
-  Ak0E4pe4SIIIgQSgGEQOcLABGYYNKiaaZGEyYjJhGTTRpiHogxGmTRiGRkNMIwhhPSbQJtpQiJkn
-  poyk9I0PUeoNNNBkeUAHqGgD0Ro0NNBoBoaMagNBoNCpNPUemp6QGmgyaPSGmQxGhkZDQbUaBkHp
-  MhoaANNMhkIyIauvSJPL4aUXjIQemQXkoaqOKqAQDIABsZALnf0yCLAyvmktzDWBCVHO6bb6kCqE
-  ZobVEhmMBjs0oQzekgs6PgZSyII8zy9mmG9To49ZlN6TaX5BxlS7cJiuICUdyjNQPIIdQs1Qqqqk
-  JZ2/BksYcU4HQyssZcpkoMco6gRc888KF9BO7BvuSuIPz7A4crBoaQB+euFU1ilz8yIBBmNBDgRX
-  pVh4zkmPiSKcqRJxcshMqh0vkKlgQDTcOujtdmnMVBZfQiPPemcHm2098VJyHBAOqOwluyIKyG92
-  JAR0CCu9SB5q9DyPHUdc5yB5CurIZHt3GM0dCiQRIN0EAcQNmTYTiHdi6B6Dc/ma0hrmSCQXBzfU
-  BEwthEg0YGaJf4u5IpwoSAO6doMA
+  SEcyMAAAAA5Db21wcmVzc2lvbj1CWkJaaDkxQVkmU1l91TAVAAAN////vFcSXL9/8H7R09C/578I
+  Ak0E4pe4SIIIgQSgGEQOcLABGYYNKgJgmhpp6mmjIZMCZNMhpgBBpkaYJpo9QaZMg02iaY2lCImK
+  emk02kmEAeoA0D01ANBoHqHqADTaj1NAAyZqA0Gg0KiYnqaepk0eoNDTCGj1A0eoyBoGjRkYBqAB
+  poNMmhkBhENSP0knlYZbqyEIYxkFdpDUS6roBDMgAGhkAqd92kEcgyeMo2MM366gpLNHjfKrhJPN
+  vdBCHAEDsYzAvzkHKxy5KWBAmh5e1nFttGChpsxrgmutRG0YrsSLWEBH9h95cbZEKFeUKYykRXHa
+  Bkt2OSgELsqqnWKeMudBR+YSZCOSHrwPz7B/Gfou7/L6QV6S0IgclBCitBVHMxMFq/vGwp5WHezM
+  JwhKTnH0OkMbmVjrAkQKR7VM2aNSXn+GzLOCzOQm0AJ1TLCpdSgnfFPcY7mGxAOyHXS1YEFVi5O9
+  I4EVBBd8VRgN4n1MAm8l6QQ+yB60hkeX/0ZZmKoQRINkEBxEDZU2HjIZMcwWRvZtbRIa5kgkGIb/
+  SkImFwIkDtQxyX+LuSKcKEg+6pgKgA==
   --===============*==-- (glob)
 
 with a specific bundle type
diff --git a/tests/test-rebase-conflicts.t b/tests/test-rebase-conflicts.t
--- a/tests/test-rebase-conflicts.t
+++ b/tests/test-rebase-conflicts.t
@@ -298,7 +298,7 @@
   2f2496ddf49d69b5ef23ad8cf9fb2e0e4faf0ac2
   bundle2-output-bundle: "HG20", (1 params) 3 parts total
   bundle2-output-part: "changegroup" (params: 1 mandatory 1 advisory) streamed payload
-  bundle2-output-part: "cache:rev-branch-cache" streamed payload
+  bundle2-output-part: "cache:rev-branch-cache" (advisory) streamed payload
   bundle2-output-part: "phase-heads" 24 bytes payload
   saved backup bundle to $TESTTMP/issue4041/.hg/strip-backup/e31216eec445-15f7a814-rebase.hg
   3 changesets found
@@ -308,7 +308,7 @@
   2a7f09cac94c7f4b73ebd5cd1a62d3b2e8e336bf
   bundle2-output-bundle: "HG20", 3 parts total
   bundle2-output-part: "changegroup" (params: 1 mandatory 1 advisory) streamed payload
-  bundle2-output-part: "cache:rev-branch-cache" streamed payload
+  bundle2-output-part: "cache:rev-branch-cache" (advisory) streamed payload
   bundle2-output-part: "phase-heads" 24 bytes payload
   adding branch
   bundle2-input-bundle: with-transaction
@@ -322,7 +322,7 @@
   adding f1.txt revisions
   added 2 changesets with 2 changes to 1 files
   bundle2-input-part: total payload size 1686
-  bundle2-input-part: "cache:rev-branch-cache" supported
+  bundle2-input-part: "cache:rev-branch-cache" (advisory) supported
   bundle2-input-part: total payload size 74
   truncating cache/rbc-revs-v1 to 56
   bundle2-input-part: "phase-heads" supported
diff --git a/tests/test-strip.t b/tests/test-strip.t
--- a/tests/test-strip.t
+++ b/tests/test-strip.t
@@ -212,7 +212,7 @@
   Stream params: {Compression: BZ}
   changegroup -- {nbchanges: 1, version: 02} (mandatory: True)
       264128213d290d868c54642d13aeaa3675551a78
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
   phase-heads -- {} (mandatory: True)
       264128213d290d868c54642d13aeaa3675551a78 draft
   $ hg unbundle .hg/strip-backup/*
@@ -851,7 +851,7 @@
   d8db9d1372214336d2b5570f20ee468d2c72fa8b
   bundle2-output-bundle: "HG20", (1 params) 3 parts total
   bundle2-output-part: "changegroup" (params: 1 mandatory 1 advisory) streamed payload
-  bundle2-output-part: "cache:rev-branch-cache" streamed payload
+  bundle2-output-part: "cache:rev-branch-cache" (advisory) streamed payload
   bundle2-output-part: "phase-heads" 24 bytes payload
   saved backup bundle to $TESTTMP/issue4736/.hg/strip-backup/6625a5168474-345bb43d-backup.hg
   updating the branch cache
diff --git a/tests/test-tags.t b/tests/test-tags.t
--- a/tests/test-tags.t
+++ b/tests/test-tags.t
@@ -733,7 +733,7 @@
       f63cc8fe54e4d326f8d692805d70e092f851ddb1
       40f0358cb314c824a5929ee527308d90e023bc10
   hgtagsfnodes -- {} (mandatory: True)
-  cache:rev-branch-cache -- {} (mandatory: True)
+  cache:rev-branch-cache -- {} (mandatory: False)
 
 Check that local clone includes cache data