Comment 27 for bug 1692795

Reviewed: https://review.opencontrail.org/33685
Committed: http://github.com/Juniper/contrail-controller/commit/72efe8e70cc65b6029d3e7f322003daadd36ec64
Submitter: Zuul (<email address hidden>)
Branch: R4.0

commit 72efe8e70cc65b6029d3e7f322003daadd36ec64
Author: Manish <email address hidden>
Date: Thu Jun 8 01:17:30 2017 +0530

BUM tree subscription skipped.

With the introduction of same RD for Tor agent for vrf, change of vnid was not
handled. In cases where a vn was added with vnid as not set or 0 and then
updated later with non zero value, vrf was not notified.
This used to result in skipping of notify registeration for the problematic vrf.
In turn subscriptions were missed.

Solution:
Handle vnid change.

Closes-bug: #1692795

Conflicts:
 src/vnsw/agent/controller/controller_vrf_export.cc
 src/vnsw/agent/oper/agent_route_walker.cc
 src/vnsw/agent/oper/vrf.cc
 src/vnsw/agent/oper/vrf.h

Conflicts:
 src/vnsw/agent/oper/vrf.h
Change-Id: I7ea7332eb1e64cb0e534f992ef5c8680a54b0313