Ticket #19471: 19471.diff

wp-includes/query.php

@@ -2689 +2689 @@
                         $where .= $clauses['where'];
                 }
 
-                if ( $this->is_tax ) {
+                if ( $this->is_tax || $this->is_category || $this->is_tag ) {
                         if ( empty($post_type) ) {
                                 // Do a fully inclusive search for currently registered post types of queried taxonomies
                                 $post_type = array();