Log Message:
py-dulwich: updated to 0.20.32

0.20.32
* Properly close result repository during test.

0.20.31
* Add GitClient.clone().

0.20.29
* Support staging submodules.
* Drop deprecated Index.iterblobs and iter_fresh_blobs.
* Unify clone behaviour of ``Repo.clone`` and
  ``porcelain.clone``, and add branch parameter for
  clone.

0.20.28
* Fix hook test on Mac OSX / Linux when dulwich is
  not installed system-wide.
* Cope with gecos being unset.

0.20.27
* Allow adding files to repository in pre-commit hook.
* Raise SubmoduleEncountered in ``tree_lookup_path``.