Core-workflow: Start using CODEOWNERS

[brettcannon]

https://github.com/blog/2392-introducing-code-owners

Since mention-bot seems to be perpetually down, we might as well drop it and switch over to the CODEOWNER file instead. Not sure how we want this to interact with https://devguide.python.org/experts/, though (e.g. script to generate CODEOWNERS from the experts file, link to CODEOWNERS from the experts file?).

[brettcannon]

FYI the free mention-bot instance we were using is down which used to do something similar for us: https://github.com/facebook/mention-bot/issues/230. So it might be time to drop mention-bot and just switch to this opt-in solution.

[Mariatta]

I started the CODEOWNERS file https://github.com/python/cpython/pull/2924

Haven't really thought how to add in the experts list from the devguide to CODEOWNERS file 😛

Should we first verify if the list of experts is accurate?

[Mariatta]

Also, the experts list contains b.p.o usernames. We need GitHub userid for CODEOWNERS.

[brettcannon]

Yep, which is why I haven't just added CODEOWNERS since there's no good solution. 😉 I would say we should drop experts.rst and just use CODEOWNERS, but that won't work since we need that for the nosy list on bugs.python.org. We could query b.p.o for people's GitHub usernames, but that doesn't translate to file globs that CODEOWNERS needs.

I think we're stuck with comments in both files saying "make sure to update the other one as appropriate" and cross-linking so people know about both files. 😞

[brettcannon]

And we should just tell people to add themselves to CODEOWNERS once the file is in instead of making bad assumptions about which files they care about.

[Mariatta]

We now have CODEOWNERS file (https://github.com/python/cpython/pull/2924), and .mention-bot has been removed from all branches (https://github.com/python/cpython/pull/2923)! :taco:

[brettcannon]

Thanks for the PRs, @Mariatta !