MB-13977: get_bucketname could return NULL
MB-13977: get_bucketname could return NULL

If get_bucketname was called without a proper sasl context
set up it would return NULL.

Change-Id: I500e6875d2f47f2043ae8bf2ad9800413df7f49f
Reviewed-on: http://review.couchbase.org/48362
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: David Haikney <429c6ca43f70a1a1104bd68d6b2835bd23bff953@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

couchbase/memcached,cloudrain21/memcached-1,daverigby/memcached,daverigby/memcached,owendCB/memcached,daverigby/kv_engine,owendCB/memcached,couchbase/memcached,owendCB/memcached,daverigby/memcached,daverigby/memcached,couchbase/memcached,daverigby/kv_engine,daverigby/kv_engine,cloudrain21/memcached-1,owendCB/memcached,couchbase/memcached,daverigby/kv_engine,cloudrain21/memcached-1,cloudrain21/memcached-1