Simplify the assertion check in TapProducer::queueBGFetch()
Simplify the assertion check in TapProducer::queueBGFetch()

Change-Id: I914d3d8bece3d5471d02b8d04804c0dbdb85b3f8
Reviewed-on: http://review.couchbase.org/15729
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Reviewed-on: http://review.couchbase.org/15839
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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