
The new paho-mqtt 1.3.0 release brings https://github.com/eclipse/paho.mqtt.python/commit/0a8cccc which prevents its use on Ubuntu Trusty's default Python interpreter. Until we upgrade to a newer Python there, stay on paho-mqtt 1.2.3 so that things keep working. Change-Id: I4ffcd8c7906c86a40f3cd8f8d83fb8208944d189