variable referenced before assignment; breaks fast-export

[Keith Hellman]

psnap$ brz fast-export --plain . | git fast-import
22:41:06 Calculating the revisions to include ...
22:41:06 Starting export of 645 revisions ...
brz: ERROR: UnboundLocalError: local variable 'path' referenced before assignment

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/breezy/commands.py", line 1017, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/breezy/commands.py", line 1206, in run_bzr
    ret = run(*run_argv)
  File "/usr/local/lib/python3.8/site-packages/breezy/commands.py", line 757, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/local/lib/python3.8/site-packages/breezy/commands.py", line 782, in run
    return class_run(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/cmds.py", line 502, in run
    return exporter.run()
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/exporter.py", line 268, in run
    self.emit_commits(interesting)
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/exporter.py", line 257, in emit_commits
    self.emit_commit(revobj, self.ref, trees[parent], trees[revid])
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/exporter.py", line 382, in emit_commit
    self.print_cmd(self._get_commit_command(ref, mark, revobj, file_cmds))
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/exporter.py", line 313, in print_cmd
    self.outf.write(b"%s\n" % cmd)
  File "/usr/local/lib/python3.8/site-packages/fastimport/commands.py", line 185, in __bytes__
    return self.to_string(include_file_contents=True)
  File "/usr/local/lib/python3.8/site-packages/fastimport/commands.py", line 237, in to_string
    [b'\n' + bytes(c) for c in self.iter_files()])
  File "/usr/local/lib/python3.8/site-packages/fastimport/commands.py", line 237, in <listcomp>
    [b'\n' + bytes(c) for c in self.iter_files()])
  File "/usr/local/lib/python3.8/site-packages/breezy/plugins/fastimport/exporter.py", line 507, in _get_filecommands
    path, renamed, tree_new.get_revision_id())
UnboundLocalError: local variable 'path' referenced before assignment

[Keith Hellman (khellman)]

Same issue exists with lp:brz-3.2.1 branch.

[Jelmer Vernooij (jelmer)]

Confirmed - this is probably due to the migration to TreeChange objects.

[Morten Kjeldgaard (mok0)]

I experience the same error, with Python 3.9.