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.
adding foo
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pushing to ../2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files