CBQE-1250: add reproducer for MB-7978

Change-Id: I48ef9f7bda8ccfefe132e4e476a29194c8eea847
Reviewed-on: http://review.couchbase.org/25896
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Deepkaran Salooja <deepkaran.salooja@globallogic.com>