This issue came up because a user is using custom tags and git describe for him is something like `debian/0.11.1+ds-1-3-ga0afcb`.
Added unittests for this.
Sorry @ryanschneider for stepping in on your fix.
Nothing is assumed now, and several checks are made. If any of the checks fail, nothing else is done in `salt.log.Logging.__new__()`.
Added a test case which will take care of possible regressions on this bug fix.