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

hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
touch b
hg add b
rm b
hg commit -A -m"comment #1" -d "1000000 0"