rebase: preserve working copy when redoing in-mem rebase on disk

When in-memory rebase runs into conflicts, we retry it on disk. But
before we do that, we abort the in-memory rebase. That is done because
even though it's mostly in memory, there are still a few state files
written (e.g. the merge state). We should make it not write those
files so we don't need to abort, but for the stable branch, let's
explicitly clear the state we need to clear instead of running the
usual abort code.

Differential Revision: https://phab.mercurial-scm.org/D5356

hgext/rebase.py

@@ -865,7 +865,11 b' def rebase(ui, repo, **opts):'
         except error.InMemoryMergeConflictsError:
             ui.warn(_('hit merge conflicts; re-running rebase without in-memory'
                       ' merge\n'))
-            _dorebase(ui, repo, action='abort', opts={})
+            # TODO: Make in-memory merge not use the on-disk merge state, so
+            # we don't have to clean it here
+            mergemod.mergestate.clean(repo)
+            clearstatus(repo)
+            clearcollapsemsg(repo)
             return _dorebase(ui, repo, action, opts, inmemory=False)
     else:
         return _dorebase(ui, repo, action, opts)

tests/test-rebase-inmemory.t

@@ -422,7 +422,6 b' In-memory rebase that fails due to merge'
   transaction abort!
   rollback completed
   hit merge conflicts; re-running rebase without in-memory merge
-  rebase aborted
   rebasing 2:177f92b77385 "c"
   rebasing 3:055a42cdd887 "d"
   rebasing 4:e860deea161a "e"
@@ -447,17 +446,10 b" Retrying without in-memory merge won't l"
   transaction abort!
   rollback completed
   hit merge conflicts; re-running rebase without in-memory merge
-  rebase aborted
-  rebasing 2:177f92b77385 "c"
-  rebasing 3:055a42cdd887 "d"
-  rebasing 4:e860deea161a "e"
-  merging e
-  warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
-  unresolved conflicts (see hg resolve, then hg rebase --continue)
-  [1]
-BROKEN: working copy change to "a" was lost
+  abort: uncommitted changes
+  [255]
   $ cat a
-  a
+  dirty
 
 Retrying without in-memory merge won't lose merge state
   $ cd ..