X -- Y -- Z <-- master
\
A -- B <-- your-cool-branch
You want to contribute the code back to the master foobar repo, but you realize there is a really dumb typo in one of your source code comments in commit A. You'd still like to submit the pull request as two commits A' and B', where A' is the fixed version of A, and B' is the same exact diff as B. How do you rewrite git history to make this happen?