git-commit --amend
The new flag is used to amend the tip of the current branch. Prepare
the tree object you would want to replace the latest commit as usual
(this includes the usual -i/-o and explicit paths), and the commit log
editor is seeded with the commit message from the tip of the current
branch. The commit you create replaces the current tip -- if it was a
merge, it will have the parents of the current tip as parents -- so the
current top commit is discarded.
It is a rough equivalent for:
$ git reset --soft HEAD^
$ ... do something else to come up with the right tree ...
$ git commit -c ORIG_HEAD
but can be used to amend a merge commit.
Signed-off-by: Junio C Hamano <junkio@cox.net>