                 cb?(err); return
             fs.writeFile @path, @live, (err) =>
                 @_start_watching_file()
-                if not err
-                    fs.exists @_backup_file, (exists) =>
-                        fs.unlink(@_backup_file)
-                cb?(err)
-
-    write_backup: (cb) =>
-        if @cm_session.content != @_last_backup
-            x = @cm_session.content
-            fs.writeFile @_backup_file, x, (err) =>
-                if not err
-                    @_last_backup = x
                 cb?(err)
 
 

                    stats_path = _stats_path
                    cb()
            (cb) =>
                fs.stat @_backup_file, (_no_backup, _stats_backup) =>
                    no_backup = _no_backup
                    stats_backup = _stats_backup
                    cb()
            (cb) =>
                if no_backup and no_master
                    # neither exist -- create
                    file = @path
                    misc_node.ensure_containing_directory_exists @path, (err) =>
                        if err

                                    cb(err)
                                else
                                    fs.close fd, cb
                else
                    # master exists
                    file = @path
                    stats = stats_path
                    cb()
            (cb) =>
                e = check_file_size(stats?.size)
