pbr/d2to1 should be build rather than runtime dependencies

Fix proposed to branch: master
Review: https://review.openstack.org/32862

pbr/d2to1 are actually requirements to run setup.py at all, so you really do need them for everything. However, you should not need git as a dependency for debian packaging, as pbr has two different facilities to work in the absence of git information.

First, for the "normal" workflow, one runs python setup.py sdist in a git clone, and this produces a python source tarball. That tarball then contains the information that is needed about versioning and authors and whatnot to not git to be consumed. Then one uses that tarball as an input to the debian packaging process.

However, if the sdist-from-git-repo step is being skipped for some reason, there is an env var, OSLO_PACKAGE_VERSION, that you can set to declare the version and skip the git version discovery. Similarly, there are SKIP_WRITE_GIT_CHANGELOG and SKIP_GENERATE_AUTHORS env vars which you can set to skip making authors and changelog files from git.

Does that help? Are there any other issues you're running in to? pbr is basically a global requirement to always be installed for all of openstack now - so I'd like to fix issues in it whenever we have them. :)