===================
Fix
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5: QoS=0 publish messages incorrectly read/write packet_id.
In Publish messages with QoS=0, packet_id is being serialized and
deserialized in violation of MQTT 3.1.1 spec (See 3.3.2.2).
https://github.com/kcallin/haka-mqtt/issues/5
6: Corrupt MqttSuback results in non-DecodeError exception.
While decoding MqttSuback, a corrupted SubscribeResult results in
a TypeError instead of DecodeError. This violates the decode
method's interface spec.
https://github.com/kcallin/mqtt-codec/issues/6