> What do you mean by "limited"?

I mean to deactivate it by default and make opt-in.

> Process groups really help to prevent to leak grandchild processes in multiprocessing tests, when tests are interrupted manually by CTRL+C or by a timeout (sadly, only when the timeout is handled by regrtest, not when it's handled by faulthandler).

I love process groups and they are awesome. But having these test being re-run on every buildbot and failing on my machine when just running test with -j is very annoying.