Checks whether the old object and new object differ; only checks
        keys which exist in the new object

def _requires_update(self, old_object, new_object):
        """Checks whether the old object and new object differ; only checks
        keys which exist in the new object
        """
        old_encoded = self.manager._encode(old_object)
        new_encoded = self.manager._encode(new_object)
        return _compare_recursive(old_encoded, new_encoded)