Find out differences between common files.
        Ensure we are using content comparison with shallow=False.

def phase3(self):
        """
        Find out differences between common files.
        Ensure we are using content comparison with shallow=False.
        """
        fcomp = filecmp.cmpfiles(self.left, self.right, self.common_files,
                                 shallow=False)
        self.same_files, self.diff_files, self.funny_files = fcomp