Import fails with DuplicateKey when generating merge previews

[James Westby]

Traceback (most recent call last):
  File "/srv/package-import.canonical.com/new/scripts/import_package.py", line 1026, in <module>
    no_existing=options.no_existing))
  File "/srv/package-import.canonical.com/new/scripts/import_package.py", line 971, in main
    possible_transports=possible_transports)
  File "/srv/package-import.canonical.com/new/scripts/icommon.py", line 1568, in generate_ubuntu_merges
    tt = tree_merger.make_preview_transform()
  File "/usr/lib/python2.5/site-packages/bzrlib/merge.py", line 788, in make_preview_transform
    return operation.run_simple()
  File "/usr/lib/python2.5/site-packages/bzrlib/cleanup.py", line 122, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/cleanup.py", line 156, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/merge.py", line 793, in _make_preview_transform
    self._compute_transform()
  File "/usr/lib/python2.5/site-packages/bzrlib/merge.py", line 826, in _compute_transform
    lambda t, c: transform.conflict_pass(t, c, self.other_tree))
  File "/usr/lib/python2.5/site-packages/bzrlib/transform.py", line 2768, in resolve_conflicts
    new_conflicts.update(pass_func(tt, conflicts))
  File "/usr/lib/python2.5/site-packages/bzrlib/merge.py", line 826, in <lambda>
    lambda t, c: transform.conflict_pass(t, c, self.other_tree))
  File "/usr/lib/python2.5/site-packages/bzrlib/transform.py", line 2846, in conflict_pass
    tt.version_file(file_id, conflict[1])
  File "/usr/lib/python2.5/site-packages/bzrlib/transform.py", line 352, in version_file
    unique_add(self._r_new_id, file_id, trans_id)
  File "/usr/lib/python2.5/site-packages/bzrlib/transform.py", line 68, in unique_add
    raise DuplicateKey(key=key)
bzrlib.errors.DuplicateKey: Key manpages-20090725200632-qyg3mf7xbif6egsw-710 is already present in map

http://package-import.ubuntu.com/status/syslinux.html