MB-17631: Fix sporadic unit test failure: test_est_vb_move
MB-17631: Fix sporadic unit test failure: test_est_vb_move

(Re-adding this back from:
http://review.couchbase.org/59420,
as the change was lost with this merge:
http://review.couchbase.org/#/c/61525/)

Change-Id: Ie3d4f327cb7f156e7579504dfda082e19cdcbd76
Reviewed-on: http://review.couchbase.org/61591
Reviewed-by: abhinav dangeti <d73ef2279de6577f7bf081737ee47554bbb7dc82@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

daverigby/ep-engine,membase/ep-engine,teligent-ru/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,couchbase/ep-engine,teligent-ru/ep-engine,owendCB/ep-engine,couchbase/ep-engine,membase/ep-engine,hisundar/ep-engine,hisundar/ep-engine,daverigby/ep-engine,daverigby/kv_engine,daverigby/kv_engine,hisundar/ep-engine,owendCB/ep-engine,membase/ep-engine,couchbase/ep-engine,teligent-ru/ep-engine,hisundar/ep-engine,couchbase/ep-engine,daverigby/kv_engine,membase/ep-engine,owendCB/ep-engine,daverigby/kv_engine,owendCB/ep-engine,daverigby/ep-engine