MB-11631 Ensure terminate is called if ensure_bucket succeeds.

Change-Id: I74af9bd5a47d2eea3054f73d9fe11b8e10103a7b
Reviewed-on: http://review.couchbase.org/39197
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>