Not quite true. You can add `exec git branch progressN HEAD` every so often in the `git rebase -i` script, or you can `edit` commits and before `git rebase --c

Not quite true. You can add `exec git branch progressN HEAD` every so often in the `git rebase -i` script, or you can `edit` commits and before `git rebase --continue` do `git branch progressN HEAD`, then later if you need to abort and restart your rebase you can rebase --onto one of those saved HEADs.