Undo a git rerere resolution that was done in a rebase

Question

Okay, so I really like the git rerere command, although I haven't really used it that much other than letting it auto-magically record my conflicts and resolve them for me. However, I did mess up one of my conflict resolutions during quite a large rebase (rebasing a really stale feature branch with the latest release).

feature -> a - b - c - d

release -> e - f - g - h

rebase/feature -> e - f - g - h .
                                 ` a' - b' - c' - d'

So, say for instance that b' has an incorrect merge (thanks to me!), and I want to re-record that. How would I do it? I've seen the git checkout --conflict option, mentioned in Rerere Your Boat, but I'm not too clear on how that works and if it applies here. Maybe I have to checkout the merge conflict state and run git rerere once I correctly resolve this conflict?

Normally, I would just commit to the tip of the rebase branch, but it is a throw away. I'm just trying to handle conflicts ahead of time, so that when I sync up with that feature team, we minimize the time it takes. Make sense?