Backup merge script throws an error if there are any missing files.
Backup merge script throws an error if there are any missing files.

Change-Id: Ib8ca2088a1066b3bd192d527f5c4df0b8e8a418a
Reviewed-on: http://review.couchbase.org/11228
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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