Unbreak "preview a random document" feature.

Change-Id: I5eb6add4bcd82a28799ec0686ea954e3d43c83f7
Reviewed-on: http://review.couchbase.org/33189
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>