Log Message:
py-dulwich: updated to 0.21.5

0.21.5

* Be more tolerant to non-3-length tuple versions.

0.21.4.1

* Support ``core.symlinks=false``.
* Deprecate ``dulwich.objects.parse_commit``.
* Fix fetching into MemoryRepo.
* Support ``init.defaultBranch`` config.
* Fix ``ObjectStore.iterobjects_subset()`` when
  hex shas are passed for objects that live in packs.
* client: Handle absolute path as redirect location in HTTP client.