MB-100: make ns_server point to correct branch

Change-Id: I9295b5b0f9ea68d58b34a0d3b10d36bda01211ff
Reviewed-on: http://review.couchbase.org/27776
Reviewed-by: Junyi Xie <junyi.couchbase@gmail.com>
Tested-by: Junyi Xie <junyi.couchbase@gmail.com>