graph.get_rev_info() raises UnboundLocalError

It seems that this error occurs if NoSuchRevision is catched but committer is anything other than ''... (but I'm not sure anyway... ;-)

$ bzr graph-ancestry graph.png
bzr: ERROR: exceptions.UnboundLocalError: local variable 'nick' referenced before assignment

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 846, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 797, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/command.py", line 13, in run_argv_aliases
    commands.Command.run_argv_aliases(self, argv, alias_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 499, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/__init__.py", line 148, in run
    max_distance=max_distance)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/graph.py", line 296, in write_ancestry_file
    relations = grapher.get_relations(collapse, max_distance)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/graph.py", line 270, in get_relations
    dot_nodes[node] = self.dot_node(node, num)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/graph.py", line 224, in dot_node
    self.branch.repository)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools/graph.py", line 106, in get_rev_info
    return committer, message, nick, date
UnboundLocalError: local variable 'nick' referenced before assignment

bzr 1.5 on python 2.5.2 (linux2)
arguments: ['/usr/bin/bzr', 'graph-ancestry', 'graph.png']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'de_DE.UTF-8'
plugins:
  builddeb /usr/lib/python2.5/site-packages/bzrlib/plugins/builddeb [0.95.0dev0]
  bzrtools /usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools [1.5.0]
  dbus /usr/lib/python2.5/site-packages/bzrlib/plugins/dbus [unknown]
  gtk /usr/lib/python2.5/site-packages/bzrlib/plugins/gtk [0.94.0]
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [unknown]
  rebase /usr/lib/python2.5/site-packages/bzrlib/plugins/rebase [0.3.0]
  svn /usr/lib/python2.5/site-packages/bzrlib/plugins/svn [0.4.10]
  xmloutput /usr/lib/python2.5/site-packages/bzrlib/plugins/xmloutput [0.5.0]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.