Test race condition between a bg_fetch and a set.
Test race condition between a bg_fetch and a set.

Cliff notes:  The set wins and the bg_fetched value is discarded.

Change-Id: Id9abf83199de41b66100c1d6926374b2b27da0cf
Reviewed-on: http://review.northscale.com/1081
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>

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