field can be None or False, Should specifically check for None.
field can be None or False, Should specifically check for None.

Change-Id: Id38e841227da1582b83ff92bbe027dd00d971fd5
Closes-Bug: 1548733

nischalsheth/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,codilime/contrail-controller,eonpatapon/contrail-controller,codilime/contrail-controller,rombie/contrail-controller,codilime/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,nischalsheth/contrail-controller,codilime/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,tcpcloud/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,codilime/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,codilime/contrail-controller,tcpcloud/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller