Feature request: make `run --forget` a `forget-results` command

[me-and]

It took me a while to work out how to get git-test to forget the results for a single commit, despite it being in the README, because I was expecting it to be part of forget-results, not run. I think it being part of run is confusing, and I'd like to request it be added to forget-results' functionality.

I'd expect the syntax to be something like git forget-results [<commit>...], where if <commit>... is not specified the command works as at present, while if it is specified, it works the same as git run --forget <commit>....

There's a small-but-greater-than-zero chance I'll manage a PR myself for this, but given the other projects currently on my plate I don't want to promise anything.

[mhagger]

I agree that it's harder than necessary to find the existing --forget option. OTOH I'm worried that tacking it on to forget-results would be dangerous if the forget-results default is to discard all results. It seems like it would be too easy to discard all of your results by accident.

If we go this route, then I think I'd propose that we make git test forget-results without an argument do nothing (but emit an error message), and require that an option like --all be passed if the user really wants to forget all results for the test. This of course would break backwards compatibility, but it's an obscure command in the first place, and it doesn't seem like all that many people are using this tool, so we could probably get away with it.