Bisect rebases... you mean that you have two release branches based on divergent upstream branches and you want to quickly test where a bug was introduced on th

Bisect rebases... you mean that you have two release branches based on divergent upstream branches and you want to quickly test where a bug was introduced on the way from the one to the other? What I would do in a rebase workflow is find the merge base (`git merge-base`) of the two release branches, and bisect from that to the release branch I'm interested in.