We've got the automerge tag on GH, it+bot make it awesome. There's one more thing I'd like to see that could help with bug hygiene: A tag to close the associated bug as "fixed" after the merge happens.
This doesn't have to be tied to automerge; in practice you'd find them used in unison somewhat often. More readily on features done on the main branch rather than bug fixes needing backports to multiple releases.
We've had such a system at work for so long I don't even remember when it was added, but it has been a great time saver. Less more bugs laying around fixed but not marked as such. Less need for triagers to manually ask someone who has the permissions to change the bug state. Less unintentionally still open bugs in the way distracting people. Good all around.
It isn't the primary way to close issues, but it helps in situations where it makes sense. I'd assume the same set of people allowed to add automerge should be allowed to add this label.
-gps