Force editor to appear for an 'hg backout' if a message or logfile aren't supplied. Pre-fill the commit message with the changeset being backed out. Fixes bug 238.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status