backout: pass 'editform' argument to 'cmdutil.getcommiteditor'
This patch passes 'editform' argument according to the format below:
COMMAND[.ROUTE]
- ROUTE: name of route, if there are two or more routes in COMMAND
In this patch, ROUTE is omitted..
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.