AttributeError

Traceback (most recent call last):
    write_tree_diff(sys.stdout, repo.object_store, commit.parents[0], commit.tree)
  File "/usr/lib/python2.7/dist-packages/dulwich/patch.py", line 209, in write_tree_diff
    for (oldpath, newpath), (oldmode, newmode), (oldsha, newsha) in changes:
  File "/usr/lib/python2.7/dist-packages/dulwich/object_store.py", line 141, in tree_changes
    want_unchanged=want_unchanged):
  File "/usr/lib/python2.7/dist-packages/dulwich/diff_tree.py", line 168, in tree_changes
    for entry1, entry2 in entries:
  File "/usr/lib/python2.7/dist-packages/dulwich/diff_tree.py", line 145, in walk_trees
    todo.extend(reversed(_merge_entries(path, tree1, tree2)))
AttributeError: 'Commit' object has no attribute 'iteritems'