Forcibly ignore some errors

--force (or FORCE=1 in a CI job) can be used to forcibly ignore some errors. Currently, it is only ignoring unfinished tests.

@chasse WDYT? Sometimes I'm going to update references one way or another (can't wait for whatever reason and don't want to wait for -dbg tests to finish). There's a benefit to still using the bot in that case. The way to pass the FORCE variable is a bit hidden (you have to go to the job page and know about FORCE), so should not be abused too much.