fix a typo

Change-Id: I6bb09b51ebcc34df3062146935fdee378bc81bad
Reviewed-on: http://review.couchbase.org/36256
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>