NPE at org.opendaylight.netvirt.elan.internal.ElanInstanceManager.remove

Seen in https://logs.opendaylight.org/releng/jenkins092/netvirt-csit-1node-openstack-newton-nodl-v2-upstream-stateful-carbon/653/odl1_karaf.log.gz

2017-06-06 04:39:39,002 | ERROR | eChangeHandler-1 | AsyncDataTreeChangeListenerBase | 291 - org.opendaylight.genius.mdsalutil-api - 0.2.1.Carbon | Thread terminated due to uncaught exception: AsyncDataTreeChangeListenerBase-DataTreeChangeHandler-1
java.lang.NullPointerException
at org.opendaylight.netvirt.elan.internal.ElanInstanceManager.remove(ElanInstanceManager.java:107)[340:org.opendaylight.netvirt.elanmanager-impl:0.4.1.Carbon]
at org.opendaylight.netvirt.elan.internal.ElanInstanceManager.remove(ElanInstanceManager.java:45)[340:org.opendaylight.netvirt.elanmanager-impl:0.4.1.Carbon]
at org.opendaylight.genius.datastoreutils.AsyncDataTreeChangeListenerBase$DataTreeChangeHandler.run(AsyncDataTreeChangeListenerBase.java:149)[291:org.opendaylight.genius.mdsalutil-api:0.2.1.Carbon]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_121]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_121]
at java.lang.Thread.run(Thread.java:745)[:1.8.0_121]