git-import from local git repository crashes

[Max Bowsher]

Attempting to import from a local (as compared with remote) git repository crashes:

  File "/home/maxb/.bazaar/plugins/git/commands.py", line 84, in run
    refs = interrepo.fetch()
  File "/home/maxb/.bazaar/plugins/git/fetch.py", line 526, in fetch
    (pack_hint, _, remote_refs) = self.fetch_objects(determine_wants, mapping, pb)
  File "/home/maxb/.bazaar/plugins/git/fetch.py", line 612, in fetch_objects
    wants = determine_wants(remote_refs)
  File "/home/maxb/.bazaar/plugins/git/fetch.py", line 525, in determine_wants
    return [rev for rev in ret if not self.target.has_revision(self.source.lookup_foreign_revision_id(rev))]
  File "/home/maxb/.bazaar/plugins/git/repository.py", line 175, in lookup_foreign_revision_id
    lambda x: None)
  File "/home/maxb/.bazaar/plugins/git/mapping.py", line 321, in import_commit
    rev.parent_ids = tuple([lookup_parent_revid(p) for p in commit.parents])
AttributeError: 'Tag' object has no attribute 'parents'

Reproduction:
git clone git://git.debian.org/collab-maint/tortoisehg.git
bzr git-import tortoisehg/ thg-bzr