[PATCH 1 of 2] commit: save commit message so it's not destroyed by rollback

[Gilles Moris]

On Sunday 22 November 2009 07:11:12 pm Greg Ward wrote:
> Rationale: if a pretxncommit hook rejects this commit, the transaction
> is rolled back and the user's commit message is irrevocably lost.
> So save a copy in .hg/message, just in case.  Also handy if the user
> deliberately rolls back a commit in order to amend it.

I would also use the .txt suffix for the message filename as Adrian Buehlmann 
suggested previously, especially if we want to advertise the file presence in 
patch #2. This will make Windows users life easier.

Regards.
Gilles.