more assert on cproxy_release_downstream()
more assert on cproxy_release_downstream()

steveyen/moxi,membase/moxi,zbase/moxi,membase/moxi,zbase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,steveyen/moxi,zbase/moxi,steveyen/moxi,zbase/moxi,zbase/moxi,steveyen/moxi,steveyen/moxi,membase/moxi,couchbase/moxi