Adding a commit message to the index

[Cameron Hutchison <lists@xdna.net>]

Is it possible to add a commit message to the index, and have it used as
the final commit message, or as the template for the final commit
message?

Witnessing AKPM's ongoing efforts on linux-kernel to get better commit
messages out of people, it seems it would be beneficial to be able to
stage a commit message and refine it over the course of the development
of the commit. The first cut is rarely the best, so being able to refine
a commit message as one can refine a commit by incrementally using the
index seems like a good idea.

I know I can use git-commit -F and store my commit message outside of
git, but it would be nice to have it in the index with the code it
comments on. That would make the commit and the message stay together
with git-stash for example. Apply this to other index-modifying
operations too.