Traceback (most recent call last):
  File "/var/lib/python-support/python2.4/trac/web/main.py", line 406, in dispatch_request
    dispatcher.dispatch(req)
  File "/var/lib/python-support/python2.4/trac/web/main.py", line 237, in dispatch
    resp = chosen_handler.process_request(req)
  File "/var/lib/python-support/python2.4/trac/versioncontrol/web_ui/browser.py", line 143, in process_request
    self._render_directory(req, repos, node, rev)
  File "/var/lib/python-support/python2.4/trac/versioncontrol/web_ui/browser.py", line 157, in _render_directory
    for entry in node.get_entries():
  File "/var/lib/python-support/python2.4/tracbzr/backend.py", line 609, in get_entries
    tree.inventory.root, child_path)
  File "/var/lib/python-support/python2.4/tracbzr/backend.py", line 780, in __init__
    path)
  File "/var/lib/python-support/python2.4/tracbzr/backend.py", line 646, in __init__
    rev_string = bzr_repo.string_rev(branch, entry.revision)
AttributeError: 'NoneType' object has no attribute 'revision'