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 a
cd a
hg init
echo foo > b
hg add b
hg ci -m "b" -d "1000000 0"
chmod -w .hg
cd ..
hg clone a b
chmod +w a/.hg # let test clean up
cd b
hg verify