KeyError in remove_index branching from svn

I have a crash during branching an svn repository. The crash file is attached.

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 842, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 1037, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.6/dist-packages/bzrlib/commands.py", line 654, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.6/dist-packages/bzrlib/builtins.py", line 1243, in run
    source_branch=br_from)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/svn/remote.py", line 117, in sprout
    return super(SvnRemoteAccess, self).sprout(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/bzrlib/bzrdir.py", line 1183, in sprout
    result_repo.fetch(source_repository, revision_id=revision_id)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 1695, in fetch
    find_ghosts=find_ghosts, fetch_spec=fetch_spec)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/svn/fetch.py", line 1293, in fetch
    self.target.unlock()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 2356, in unlock
    self.abort_write_group()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repository.py", line 943, in abort_write_group
    self._abort_write_group()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 2249, in _abort_write_group
    self._pack_collection._abort_write_group()
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 2054, in _abort_write_group
    self._remove_pack_indices(self._new_pack)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 1831, in _remove_pack_indices
    self.revision_index.remove_index(pack.revision_index, pack)
  File "/usr/lib/python2.6/dist-packages/bzrlib/repofmt/pack_repo.py", line 654, in remove_index
    del self.index_to_pack[index]
KeyError: <bzrlib.btree_index.BTreeBuilder object at 0xbc854ec>