wishlist: make it possible to amend commit messages after push to remote

[Jarkko Hietaniemi <jhi@iki.fi>]

Not for the first time, and probably not for the last, I pushed a commit
upstream without adding a link for the bug report as I was meaning to.

Or it could have been...

- Simple typos.

- Broken URLs.

- The impossibility of two consecutive commits referring to each other
because the older one cannot know what the newer one will be called.

- The following morning / 5 minutes / 5 second later thinking of
an additional factoid that would've been great to have in the
commit message.

In general, I find the fact that once a commit has left the building,
it goes into your permanent record, and cannot be changed, ever, to be
very, very annoying. I get the cryptographic "sealing" with all the
preceding changes, but...

Not that I've thought this through... but couldn't there be a bunch of
"aliases" (new SHAs) for a commit?  The original one being the
"master", but as/if the commit message is changed, it could get new
SHAs.  Sort of separating the real data of the commit, and the metadata?