Log Message:
py-setuptools: update to 39.1.0.

v39.1.0
-------

* #1340: Update all PyPI URLs to reflect the switch to the
  new Warehouse codebase.
* #1337: In ``pkg_resources``, now support loading resources
  for modules loaded by the ``SourcelessFileLoader``.
* #1332: Silence spurious wheel related warnings on Windows.