Improve throughput for packages with .changes entries only (e.g. added bug refs)
Currently, factory-auto adds opensuse-review-team and staging unconditionally to all submissions it accepts.
In order to assist devs with the factory-first process, we should no longer demand staging for submissions that ONLY have a diff in the .changes file (no diff in .spec or other source files).
Of course, in theory, the outcome of the package COULD be changed based on the .changes file, but this is a theoretical corner case.
Skipping the additional reviews and staging for such simple changes will allow for a larger throughput, further helping the SLE staff to get their packages quickly corrected in Factory