
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 the MQTT callback plugin for Ansible will remain functional. Change-Id: I2d8d5f74a3a8244da226d18365650780d3350d1f