MB-8145: unbreak bucket auth

Change-Id: I99bf063b4397002eb02b748aced6e6fbb481cc55
Reviewed-on: http://review.couchbase.org/28079
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>