rebase: make sure merge state is cleaned up for no-op rebases (issue5494)

If a rebase ends up doing a no-op commit, make sure the merge state is still cleaned up.

hgext/rebase.py

@@ -420,6 +420,11 b' class rebaseruntime(object):'
                                            editor=editor,
                                            keepbranches=self.keepbranchesf,
                                            date=self.date)
+                    if newnode is None:
+                        # If it ended up being a no-op commit, then the normal
+                        # merge state clean-up path doesn't happen, so do it
+                        # here. Fix issue5494
+                        mergemod.mergestate.clean(repo)
                 else:
                     # Skip commit if we are collapsing
                     repo.dirstate.beginparentchange()

tests/test-rebase-interruptions.t

@@ -272,3 +272,34 b' Abort the rebasing:'
   o  0:public 'A'
   
   $ cd ..
+
+Make sure merge state is cleaned up after a no-op rebase merge (issue5494)
+  $ hg init repo
+  $ cd repo
+  $ echo a > a
+  $ hg commit -qAm base
+  $ echo b >> a
+  $ hg commit -qm b
+  $ hg up '.^'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ echo c >> a
+  $ hg commit -qm c
+  $ hg rebase -s 1 -d 2 --noninteractive
+  rebasing 1:fdaca8533b86 "b"
+  merging a
+  warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]
+  $ echo a > a
+  $ echo c >> a
+  $ hg resolve --mark a
+  (no more unresolved files)
+  continue: hg rebase --continue
+  $ hg rebase --continue
+  rebasing 1:fdaca8533b86 "b"
+  note: rebase of 1:fdaca8533b86 created no changes to commit
+  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/fdaca8533b86-7fd70513-backup.hg (glob)
+  $ hg resolve --list
+  $ test -f .hg/merge
+  [1]
+