We first set up Mergify in 2020 to automerge PRs once certain conditions were met: CI has passed, PR is approved, automerge label added: #4931.

Since then, GitHub has added native automerge which is a bit nicer to use: no need to add a label, and while the CI is still running, the "Merge pull request" button becomes an "Enable auto-merge" button, which will do the merge when the CI passes.

Docs: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/incorporating-changes-from-a-pull-request/automatically-merging-a-pull-request

I've created a ruleset for the main branch at 🔒 https://github.com/python-pillow/Pillow/settings/rules/7135275. There are lots of settings, but I've mirrored the Mergify ones:

Require these status checks to pass:

• Docker Test Successful
• Lint
• MinGW
• Test Successful
• Windows Test Successful
• (Cygwin omitted as it'll be removed in Drop support for Python 3.9 #9119 )

Also left this enabled, because we don't want to accidentally delete main:

• Restrict deletions
  Only allow users with bypass permissions to delete matching refs.

We don't need to add a label, because it's now signalled by clicking "Enable auto-merge".

And we don't require explicit approval, because that's also implicit when clicking "Enable auto-merge" (similarly, for a PR where the CI has already passed, we don't require explicit approvals).

If for some reason a status check fails but we still want to merge (maybe some dependency is temporarily failing to download because a server is down), as admins we can still click to bypass the rules and merge.