Add missing testing for the new GitLab API v4 support.
Review Request #1842 — Created Feb. 3, 2020 and updated
Some unit tests were missing from the GitLab API v4 change. We had the beginnings of a function for checking repositories against the v4 API, but it never actually performed any checks (and was missing a necessary part of the payload to make the checks happen). This fills in the missing logic, and adds a utility function for setting the API version for a test so spies don't need to be repeated in several places. Testing Done: Unit tests pass. Reviewed at https://reviews.reviewboard.org/r/9789/