This can be done now.

subject: [issue25] [status=testing]

-- 
http://selenic.com : development and support for Mercurial and Linux

Yeah, let's close this.

I'm not sure we want it -> deffered

This has shell escaping security issues. Better to have a quick Python script.

I added a (not tested) example commit hook in the wiki
(http://www.selenic.com/mercurial/wiki/index.cgi/CommitHook):

if you add "fix:issueNUMBER" in your changeset description, it will send a mail
to close issueNUMBER.

#!/bin/sh

ISSUE=`hg log -vr $NODE | grep -o "\<fix:[[:alnum:]]*" |head -n 1 | sed s/fix://`
[ -z $ISSUE ] && exit
SUBJECT=`hg log -r $NODE | grep "^summary:" | cut -b 14-`
hg log -vr $NODE | mail -s "[$ISSUE] [status=resolved] commit: $SUBJECT"
roundup@example.com