'When a response callback adds another callback, that new callback should still be called.
See https://github.com/Pylons/pyramid/pull/1373'

def test__process_response_callback_adding_response_callback(self):

    inst = self._makeOne()
    def callback1(request, response):
        request.called1 = True
        response.called1 = True
        request.add_response_callback(callback2)
    def callback2(request, response):
        request.called2 = True
        response.called2 = True
    inst.add_response_callback(callback1)
    response = DummyResponse()
    inst._process_response_callbacks(response)
    self.assertEqual(inst.called1, True)
    self.assertEqual(inst.called2, True)
    self.assertEqual(response.called1, True)
    self.assertEqual(response.called2, True)
    self.assertEqual(len(inst.response_callbacks), 0)
