MB-100 Fix false failover warning.

Which appeared because misc:uniqc expects sorted input.

Change-Id: Ib183352c6915b6b852b77569ffd17b1c3cfa4204
Reviewed-on: http://review.couchbase.org/30077
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>