One of the more toilsome bits of coding I do personally is rebasing. I have a patch to add application-time temporal tables to the Postgres project, and I've been rebasing it for several years now. It's a pretty big patch (actually a series of four patches), so there are almost always non-trival conflicts to deal with. If ChatGPT could do that for me it would be awesome.
But it's probably the hardest thing for an LLM to do. It's not a routine program that has been written thousands of times across Github projects and StackOverflow posts. Every rebase is completely new.
OTOH it would be awesome if git had just a bit more intelligence around merge conflicts. . . .