Comment 11 for bug 1801474

Reviewed: https://review.opencontrail.org/48899
Committed: http://github.com/Juniper/contrail-controller/commit/f4fdbf871d088907475c88069d46a3e23aadbf3d
Submitter: Zuul v3 CI (<email address hidden>)
Branch: R5.0

commit f4fdbf871d088907475c88069d46a3e23aadbf3d
Author: Shivayogi Ugaji <email address hidden>
Date: Mon Nov 5 22:07:18 2018 -0800

db_resync_done lock is used to indicate the amqp thread to wait for resync to
complete. In this case, when we call SchemaTransformer.destroy_instance()
due to Casandra connection failure, this lock remains locked blocking
destroy_instance. destroy_instance calls _vnc_subscribe_callback to drain the
amqp queue which waits infinitely for db_resync_done lock to be released.
This fix releases db_resync_done lock so that destroy_instance doesnt get
blocked.

Change-Id: Ic81fd0acda0fd4d43b3bfd061b47527b150b9096
Closes-Bug: #1801474
(cherry picked from commit 6a29730679db2375c0eee7006de2665b53cf979d)