Revising commit message?

[Neal Becker]

On Tuesday 18 December 2007, Patrick Mézard wrote:
> Neal Becker a écrit :
> > I see I made a mistake in one of my commit messages.  Any way to revise
> > the message (from several commits back)?
>
> Once published no.

What is the precise definition of "published"?  I'm guessing it means that 
other repos that _are not exact duplicates_ have pulled this changeset.  How 
about if I have several clones, but they are all exact duplicates?

> Use MQ otherwise.
How?