Comment 7 for bug 1576818

Reviewed: https://review.opencontrail.org/19801
Committed: http://github.org/Juniper/contrail-controller/commit/327a706e411ff375d07e506957234bf1b3bd3dc7
Submitter: Zuul
Branch: R3.0

commit 327a706e411ff375d07e506957234bf1b3bd3dc7
Author: Prabhjot Singh Sethi <email address hidden>
Date: Mon May 2 15:13:07 2016 +0530

Fix agent crash in FlowHandler::Run

Issue:
------
for a flow on re-evaluation if it moves from non-NAT to
NAT, instead of marking it as short flow and getting
removed it was getting re-enqueued to partition 0 with
IPC pointer being reset, causing NULL ptr access while
processing the re-enqueued message

Fix:
----
do not allow re-enqueuing of a flow update message

Closes-Bug: 1576818
Change-Id: I96a42eda7ae941da022915fd3bfe8c114a1fe437
(cherry picked from commit 48665aab1b1e62f29eecbbf86394a792f729317f)