Yes, that’s basically what I was thinking. New test suite runs against old code, new tags are created if the tests pass.
As for code coverage, that is always a problem, and not one to sneeze at.
So follow me here. I do a lot of tech selection for teams. Not just which libraries have he features we need, which ones are going to result in. One pair programming due to human error.
If I see that the poorly documented (accidental?) feature I care about has poor code coverage, should I use it? Should I use it and file a PR with pinning tests?
Using tests across versions is a definitely a trick to consider but your coverage may vary. Probably better to do it in addition to other methods.