bzr merge fails with changed/removed file, hard to recover

Situation: some SuSE guy autotoolized pmount a while ago, which involved quite a lot of file renames, moves, and deletions. The autotoolized version which branched off an earlier pmount version is at http://people.ubuntu.com/~pitti/bzr/pmount-autotools/ .

I tried to merge this branch against pmount main; a snapshot of the version I merged to is at http://people.ubuntu.com/~pitti/bzr/pmount.atmerge/:

$ bzr merge ../pmount-autotools/
bzr: WARNING: Diff3 conflict encountered in /home/martin/src/pmount-head/./CHANGES
bzr: ERROR: Contents mismatch deleting /home/martin/src/pmount-head/./Makefile
  at /usr/lib/python2.4/site-packages/bzrlib/changeset.py line 1033, in wrong_old_contents()

the CHANGES warning is fine, I have to resolve a conflict; but the ERROR spoils the merge in two different ways: first, it is not helpful in the first place, and second it leaves the tree in an inconsistent state:

$ bzr status
removed:
  pmount-hal.1
  pmount-hal.c
  pmount.allow
  pumount.1
  pumount.c
modified:
  CHANGES
unknown:
  CHANGES.BASE
  CHANGES.OTHER
  CHANGES.THIS
  bzr-tree-change
conflicts:
  CHANGES

That means that quite a bunch of the source files have been removed, but they weren't created in the new location (etc/pmount.allow, or src/pmount.c) (these files have been moved in the autotools branch). The bzr-tree-change directory clutters up the working tree, and bzr revert fails:

p$ bzr revert
bzr: ERROR: bzr-tree-change contains files from a previous failed merge operation.
  at /usr/lib/python2.4/site-packages/bzrlib/changeset.py line 1094, in apply_changeset()

After manually removing the directory, bzr revert works better: it adds back the removed files and just leaves the CHANGES conflict laying around (which is still a bug, but sucks much less, and should be in a separate report).

I was able to work around this bug by manually removing Makefile before merging, BTW.