filemerge._idump: drop no longer necessary 'if r:' check Cleanup from an earlier patch to make premerge be directly called from the main filemerge function.

filemerge._merge: drop no longer necessary 'if r:' check Cleanup from an earlier patch to make premerge be directly called from the main filemerge function.

revset: delete _updatedefaultdest as it has no users The revset is not used anywhere anymore. We delete the function until we use (and therefore test it again).