CI: for-every-commit: Better attempts at finding upstream repo
for-every-commit needs to know what main is, so it can test every new commit. The problem is, whose main, where? Previously we assumed origin
but this goes wrong when the repo is a fork. I'm pretty sure this is what is happening here: !344 (comment 3030463)
This new code is still not great but I don't see a much better way. I will make a ticket.