[Shish2k]

JJ, Gerrit, codebutler, and I think a couple of others have all basically agreed upon a syntax for change IDs and they are converging their prior ad-hoc formats into one; but last time I checked, the request to the upstream git team of "please don't silently drop the change-id header during rebase or amend" was met with bike-shedding about all the other hypothetical benefits that alternative formats could hypothetically provide, so universal support for the header as used in practice today is still missing D:

(I would love to be proven wrong if there's been some progress that I didn't get the memo about ^^)

[steveklabnik]

This is roughly the current state of things as I know about it, that said I haven't read a lot of git's mailing list lately so it's possible that there have been some other developments.