ext-gw resolve is delay - causing csit failure

The tests run from 05:18
During the tests we can see on karaf log that mac address is null and just after the test it succeed on resolving mac address:

2017-01-11 05:18:00,412 | INFO | ol-47-thread-362 | ExternalNetworkGroupInstaller | 326 - org.opendaylight.netvirt.natservice-impl - 0.3.2.SNAPSHOT | Installing ext-net group 205023 entry for subnet 7abfba0b-0965-4e85-9912-9e36b188eed8 with macAddress null (extInterfaces: [101507831905694:br-physnet1-pa:flat, 189602412575740:br-physnet1-pa:flat, 27191931408474:br-physnet1-pa:flat])

2017-01-11 05:19:44,546 | INFO | ol-47-thread-363 | ExternalNetworkGroupInstaller | 326 - org.opendaylight.netvirt.natservice-impl - 0.3.2.SNAPSHOT | Installing ext-net group 205023 entry for subnet 7abfba0b-0965-4e85-9912-9e36b188eed8 with macAddress f6:00:00:ff:01:01 (extInterfaces: [101507831905694:br-physnet1-pa:flat, 189602412575740:br-physnet1-pa:flat, 27191931408474:br-physnet1-pa:flat])