Fix transport_maps function for non-existent domains The postfix_transport_maps function had a bug causing 2012-04-15 17:40:22 CEST LOG: statement: SELECT transport FROM postfix_transport_map('logcheck', 'domine.madduck.net'); 2012-04-15 17:40:22 CEST ERROR: query returned no rows when the domain was not in the database. This would make did be NULL and make the query fail. This patch moves the tid query until after a check for did. If the latter is NULL, the function RETURNs (rather than fails).