diff --git a/tests/test-rebase-obsolete.t b/tests/test-rebase-obsolete.t
--- a/tests/test-rebase-obsolete.t
+++ b/tests/test-rebase-obsolete.t
@@ -2136,3 +2136,79 @@
   |/
   o  0: 1994f17a630e 'A' bookmarks:
   
+Rebase a merge where some of the ancestors on both sides of the merge
+have successors that have linearized.
+
+  $ echo alpha > alpha
+  $ hg ci -Am alpha alpha
+  created new head
+  $ echo beta > beta
+  $ hg ci -Am beta beta
+  $ hg co 5
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ echo gamma > gamma
+  $ hg ci -Am gamma gamma
+  created new head
+  $ echo delta > delta
+  $ hg ci -Am delta delta
+  $ hg merge 9
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m merge
+  $ hg co 7
+  2 files updated, 0 files merged, 4 files removed, 0 files unresolved
+  $ echo alphaprime > alpha
+  $ hg ci -Am alphaprime alpha
+  $ echo gammaprime > gamma
+  $ hg ci -Am gammaprime gamma
+  $ hg debugobsolete `hg log -r 8 -T'{node}'` `hg log -r 13 -T'{node}'`
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  2 new orphan changesets
+  $ hg debugobsolete `hg log -r 10 -T'{node}'` `hg log -r 14 -T'{node}'`
+  1 new obsolescence markers
+  obsoleted 1 changesets
+  1 new orphan changesets
+  $ hg log -GT "{rev}: {node|short} '{desc}'"
+  @  14: c87966a2bac9 'gammaprime'
+  |
+  o  13: 6405e0193644 'alphaprime'
+  |
+  | *    12: 608f8c33b2dd 'merge'
+  | |\
+  | | *  11: 8415a35bb872 'delta'
+  | | |
+  | | x  10: 4219fc7517e7 'gamma'
+  | | |
+  | * |  9: 6cf04930d1a4 'beta'
+  | | |
+  | x |  8: a71f025d4776 'alpha'
+  | |/
+  o |  7: 9c86c650b686 'C'
+  | |
+  o |  6: 9b87b54e5fd8 'B'
+  |/
+  o  5: 39adf30bc1be 'conflict with d'
+  |
+  o  4: 9c1e55f411b6 'E'
+  |
+  | *  3: 67a385d4e6f2 'D'
+  | |
+  | x  2: 49cb3485fa0c 'C'
+  | |
+  | x  1: 6c81ed0049f8 'B'
+  |/
+  o  0: 1994f17a630e 'A'
+  
+  $ hg co 12
+  4 files updated, 0 files merged, 2 files removed, 0 files unresolved
+Sadness: the rebase doesn't work, because it's confused by the
+linearization that's taken place. :(
+  $ hg rebase -d 14
+  note: not rebasing 8:a71f025d4776 "alpha", already in destination as 13:6405e0193644 "alphaprime"
+  rebasing 9:6cf04930d1a4 "beta"
+  note: not rebasing 10:4219fc7517e7 "gamma", already in destination as 14:c87966a2bac9 "gammaprime" (tip)
+  rebasing 11:8415a35bb872 "delta"
+  rebasing 12:608f8c33b2dd "merge"
+  abort: rebasing 12:608f8c33b2dd will include unwanted changes from 8:a71f025d4776 or 10:4219fc7517e7
+  [255]