Make the read_versioninfo to match write_versioninfo.
Additionally, there is an edge case where if the code is installed from a
github zipball, versioning info is missing. Now that we're using this,
there should be virtual no instances where a zipball will be easier or
less cost than an sdist created tarball, all of which should be public and
accessible, but during the transition, we need to account for the codepath.
Change-Id: Icd3fe97c6341bb04da27adc55a85f1ab6b525c46
Monty Taylor
089d509f35