Cause: In some (as-yet-undetermined) circumstances, nodes were apparently receiving a duplicate out-of-order HostSubnet "deleted" event from the master. Consequence: When processing the duplicate event, the node could end up deleting OVS flows corresponding to an active node, causing pods on the two nodes to be unable to communicate with each other. (This was most noticeable when it happened to a node hosting the registry.) Fix: The HostSubnet event-processing code will now notice that the event is a duplicate and ignore it. Result: OVS flows are not deleted, and pods can communicate.