Fixes to builds on RHEL with mock/chroot
This PR modifies the build sequence in a few ways:
- modified
setup_utils.py
to only requireGitPython >= 2.1.8
if the installed version ofgit
itself is>= 2.15.0
- install
GitPython>=2.1.8
manually for CI builds on RHEL - upgrade
setuptools
after the package build to help installing from requirements files