Ironic node fails to power on during deployment due to: unsupported operand type(s) for +: 'int' and 'NoneType'

Issue

2018-04-05 20:55:05.415 25826 DEBUG ironic.common.glance_service.base_image_service [req-c9fac81a-abc3-420d-9154-117942a4bdf6 44c21dbd81ad43aaaa8a5f89517484aa 1de23097da384f6180aa7664416a785c - default default] Getting image metadata from glance. Image: ec861a25-93c1-4ab0-806a-8383d46a124f _show /usr/lib/python2.7/site-packages/ironic/common/glance_service/base_image_service.py:140
2018-04-05 20:55:05.531 25826 DEBUG ironic.common.states [req-c9fac81a-abc3-420d-9154-117942a4bdf6 44c21dbd81ad43aaaa8a5f89517484aa 1de23097da384f6180aa7664416a785c - default default] Exiting old state 'deploying' in response to event 'fail' on_exit /usr/lib/python2.7/site-packages/ironic/common/states.py:228
2018-04-05 20:55:05.532 25826 DEBUG ironic.common.states [req-c9fac81a-abc3-420d-9154-117942a4bdf6 44c21dbd81ad43aaaa8a5f89517484aa 1de23097da384f6180aa7664416a785c - default default] Entering new state 'deploy failed' in response to event 'fail' on_enter /usr/lib/python2.7/site-packages/ironic/common/states.py:234
2018-04-05 20:55:05.579 25826 INFO ironic.conductor.task_manager [req-c9fac81a-abc3-420d-9154-117942a4bdf6 44c21dbd81ad43aaaa8a5f89517484aa 1de23097da384f6180aa7664416a785c - default default] Node b4ebad15-7890-4737-b3ff-1558e58fa320 moved to provision state "deploy failed" from state "deploying"; target provision state is "active"
2018-04-05 20:55:05.580 25826 ERROR ironic.conductor.manager [req-c9fac81a-abc3-420d-9154-117942a4bdf6 44c21dbd81ad43aaaa8a5f89517484aa 1de23097da384f6180aa7664416a785c - default default] Error while preparing to deploy to node b4ebad15-7890-4737-b3ff-1558e58fa320: unsupported operand type(s) for +: 'int' and 'NoneType'