MB-100: add reb in dgm testcase

Change-Id: Ica42803e5aec30abd31c0ce5bf4e3e95a7ac7e56
Reviewed-on: http://review.couchbase.org/27615
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>