git: Breaks pushing rename from subdirectory to root

  affects bzr-git
  status triaged
  importance low

bzr-git breaks pushing subvertpy into git:

gwenhwyvar:~/src/subvertpy/trunk% BZR_PDB=1 bzr.dev dpush
--no-rebase ../subvertpy.git
bzr: ERROR: exceptions.AssertionError: Invalid sha for <Tree
aaf7612cf9ef2cb1ff7de69426881183d760b6d0>:
c6db75d0696219c2b8fa5dff13dd3900f34a38ce

Traceback (most recent call last):
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/commands.py", line 911, in
exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/commands.py", line 1111, in
run_bzr
    ret = run(*run_argv)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/commands.py", line 689, in
run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/commands.py", line 704, in
run
    return self._operation.run_simple(*args, **kwargs)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/cleanup.py", line 135, in
run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/cleanup.py", line 165, in
_do_with_cleanups
    result = func(*args, **kwargs)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/foreign.py", line 319, in
run
    push_result = source_branch.lossy_push(target_branch)
  File "/home/jelmer/src/bzr/bzr.dev/bzrlib/branch.py", line 1094, in
lossy_push
    return lossy_push(stop_revision)
  File "/home/jelmer/.bazaar/plugins/git/branch.py", line 704, in
lossy_push
    update_refs)
  File "/home/jelmer/.bazaar/plugins/git/push.py", line 213, in
dfetch_refs
    revidmap, gitidmap = self.dfetch(new_refs.values())
  File "/home/jelmer/.bazaar/plugins/git/push.py", line 240, in dfetch
    todo, roundtrip=False):
  File "/home/jelmer/.bazaar/plugins/git/push.py", line 72, in
import_revisions
    git_commit = self.import_revision(revid, roundtrip)
  File "/home/jelmer/.bazaar/plugins/git/push.py", line 85, in
import_revision
    roundtrip):
  File "/home/jelmer/.bazaar/plugins/git/object_store.py", line 373, in
_revision_to_objects
    root_tree = self[self[base_sha1].tree]
  File "/home/jelmer/.bazaar/plugins/git/object_store.py", line 570, in
__getitem__
    unusual_modes, expected_sha=sha)
  File "/home/jelmer/.bazaar/plugins/git/object_store.py", line 461, in
_reconstruct_tree
    _check_expected_sha(expected_sha, tree)
  File "/home/jelmer/.bazaar/plugins/git/object_store.py", line 135, in
_check_expected_sha
    expected_sha))
AssertionError: Invalid sha for <Tree
aaf7612cf9ef2cb1ff7de69426881183d760b6d0>:
c6db75d0696219c2b8fa5dff13dd3900f34a38ce