Check membership in set instead of list, in scale *way* more performant.
Check membership in set instead of list, in scale *way* more performant.

Change-Id: I23dc40fa954e8d82be9b460affb57ff44673d6ee
Partial-Bug: 1589014

tcpcloud/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller