Piotr Piastucki authored Mar 12, 2010 and Kai Willadsen committed Mar 14, 2010

A new class called AutoMergeDiffer is extracted from Merger class to
separate the functionality. AutomMergeDiffer is supposed to be a
drop-in replacement for Differ while Merger class handles file merging
only. This change also prepares ground for adding 2 file merge support
to Merger. Moreover, some redundant code is removed from
AutoMergeDiffer and replaced with a proper call to Differ._auto_merge