Add a status check for reverted commits

[berkerpeksag]

Currently, it's hard to know why a commit has been reverted. I wonder if we should require to have a "Reason:" field in commit messages.

bedevere seems like a good tool to implement this.

[Mariatta]

Maybe we can start by mentioning this in the devguide 🤔

[brettcannon]

You might want to talk to python-committers or python-dev about this before implementing it as I have not heard this issue brought up prior to this issue.

[brettcannon]

I should also mention core-workflow is also an acceptable place to ask about this. My point is that since this will be front and centre for everyone it should be discussed at least a little bit before it gets turned on.

[berkerpeksag]

I don't really have time and motivation to start an endless thread on a mailing list. This was briefly mentioned by other core developers (I think the last time I read something about this was written by @terryjreedy) on various places over the past few years, but unfortunately I don't have a link.

[Mariatta]

This is the most recent message about revert commit message in python-committers:

https://mail.python.org/pipermail/python-committers/2017-April/004389.html

[brettcannon]

I agree that people should be filling in a message, I just don't know if requiring a "Reason:" prefix is necessary instead of simply telling people they are expected to give a reason. It's one of those questions of whether we need an explicit check or people just need to pick up the habit?

[terryjreedy]

Although I clicked the 'like' button for the message that said 'require Reason: field', I am inclined to what Brett said. I would prefer a first line of 'Revert xyz because it broke Window buildbot' to having the reason buried in the details, if any. I also think we should carefully pick what is mechanically required.

[Mariatta]

I'm good with just asking people to give a reason, and not needing a status check for it :)

[brettcannon]

OK, with the update @Mariatta did to the devguide for providing guidance to have people say why something was reverted I think this can probably be closed. OK with you @berkerpeksag ?

[berkerpeksag]

SGTM, thanks @Mariatta!