MB-100: fix xdcr replication_while_rebooting_a_non_master_destination_node

Change-Id: I0c070fe23084be4ca2d86fd2c45f4e5f94c240e2
Reviewed-on: http://review.couchbase.org/24926
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>