Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 919, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 1124, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 672, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 694, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/plugins/builddeb/cmds.py", line 1371, in run
    conflicts = tree.merge_from_branch(source_branch, to_revision=revid)
  File "/usr/lib/python2.7/dist-packages/bzrlib/decorators.py", line 218, in write_locked
    result = unbound(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/workingtree.py", line 806, in merge_from_branch
    conflicts = merger.do_merge()
  File "/usr/lib/python2.7/dist-packages/bzrlib/merge.py", line 686, in do_merge
    merge = operation.run_simple()
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/merge.py", line 653, in _do_merge_to
    hook(merge)
  File "/usr/lib/python2.7/dist-packages/bzrlib/plugins/builddeb/__init__.py", line 206, in pre_merge
    pre_merge_quilt(merger)
  File "/usr/lib/python2.7/dist-packages/bzrlib/plugins/builddeb/__init__.py", line 252, in pre_merge_quilt
    merger.this_branch, force=True)
  File "/usr/lib/python2.7/dist-packages/bzrlib/plugins/builddeb/merge_quilt.py", line 89, in tree_unapply_patches
    revision_id=orig_tree.last_revision(), accelerator_tree=orig_tree)
AttributeError: 'DirStateRevisionTree' object has no attribute 'last_revision'