I'm against having files for random releases in the source tree. If someone reports a bug tagging a specific release, it's easier to just tag one of the files in `test/data` for that one release instead of trying to figure out if one of the releases in the files here might cause the same problem or not.

> The purpose of having tagged files is for regression testing - you can retag them and see if anything changes.

That sounds a lot like the existing tests in `test/formats.py` to me - are they insufficient for your purposes? If so, is there any chance to extend them to cover your test cases?