Feature request: rebase -i inside of rebase -i

I'm cleaning up a patch series for submission, and came across a fixup in patch #4/20 that belongs in #2/20.

Unfortunately, I can't go back two patches to apply the fix until I get to the end of the current rebase, then go back down to clean it up. :-(

Thinking about it, I realized that a rebase in a rebase is a perfectly well defined operation. *If* you don't bother setting a new abort point (it's not a fully nested transaction), *and* require that the tree be clean (no stashing allowed; create a WIP commit instead), it's just a matter of putting some commits back on the front of the todo-list and checking out the old version.

This would make rebase work more like quilt.

I'm not sure how difficult this would be, but it might be worth looking into. (Possibly gated by an extra option like --nested.)

(A second thing that would be nice would be a documented way to break out of a reword and change the commit. A few times I've been improving the documentation of a patch and realized that I should change the function name.)