commit: save commit message so it's not destroyed by rollback.
(
issue1635)
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/last-message.txt, just in case. Also handy if
the user deliberately rolls back a commit in order to amend it.
changeset: 0:9426b370c206
tag: tip
user: My Name <myname@example.com>
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 1:4997f15a1b24
tag: tip
user: foo@bar.com
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 2:72b8012b424e
tag: tip
user: foobar <foo@bar.com>
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
changeset: 3:35ff3067bedd
tag: tip
user: foo@bar.com
date: Mon Jan 12 13:46:40 1970 +0000
summary: commit-1
abort: no username supplied (see "hg help config")
No username found, using user@host instead
transaction abort!
rollback completed
abort: empty username!