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.
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)