Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/commands.py", line 911, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/commands.py", line 1111, in run_bzr
    ret = run(*run_argv)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/commands.py", line 689, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/commands.py", line 704, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/cleanup.py", line 135, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/cleanup.py", line 165, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/builtins.py", line 1440, in run
    old_tip=old_tip)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/workingtree.py", line 2257, in update
    return self._update_tree(old_tip, change_reporter, revision)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/mutabletree.py", line 49, in tree_write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/workingtree.py", line 2312, in _update_tree
    self.set_root_id(to_root_id)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/mutabletree.py", line 49, in tree_write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/bzrlib/workingtree.py", line 2170, in set_root_id
    'WorkingTree.set_root_id with fileid=None')
ValueError: WorkingTree.set_root_id with fileid=None