A neat trick that could come in real handy at times would be to teach git range-diff to compare a local branch to a patch series that is provided as an mbox, e.g. to use git range-diff to see
whether a given patch series on the mailing list has made it into git.git's pu branch yet.

We could introduce range-diff mbox:<file> A..B for that, for example.

This would still require some scripting to e.g. pull down the mbox files of a patch series from https://public-inbox.org/git.

But it would solve the problem where current range-diff requires local branches, and therefore the user would have to find a commit where the patch series actually applies first.