Handle deferred error condition - make test_14 pass

  Tests03_Protocol
    test_09_badRequestResponse ...                                         [OK]
    test_10_badRequests ...                                                [OK]
    test_11_handlerException ...                                           [OK]
    test_12_handlerReturnsDeferred ...                                     [OK]
    test_13_handlerReturnsBadDeferred ...                                  [OK]
    test_14_handlerReturnsDeferredWithFailure ...                          [OK]
    test_15_timeout ...                                                  [FAIL]