MB-11749: Prevent GetLocked response from masking NOT_MY_VB

Change-Id: Ibd1e8fa8a1635746c838a753b46d3e93096fd5b8
Reviewed-on: http://review.couchbase.org/39450
Reviewed-by: Sundararaman Sridharan <sundar@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>