Given one existing commit, revert the change the patch
introduces, and record a new commit that records it. This
requires your working tree to be clean (no modifications from
the HEAD commit).
This is based on what Linus posted to the list, with
enhancements he suggested, including the use of -M to attempt
reverting renames.
Signed-off-by: Junio C Hamano <junkio@cox.net>