Keystonemiddleware already uses PBR:-
setuptools.setup(
setup_requires=['pbr>=1.8'],
pbr=True)
This patch removes `MANIFEST.in` file as pbr generates a
sensible manifest from git files and some standard files
and it removes the need for an explicit `MANIFEST.in` file.
Change-Id: I9886df7fc8cfe3d35795f475ddc20f4006521694
Closes-Bug: #1608980