Ticket #12891: t21891-isset-taxonomy-rewrite-hierarchical.diff

wp-includes/query.php

@@ -1503 +1503 @@
                                         'operator' => 'IN'
                                 );
 
-                                if ( $t->rewrite['hierarchical'] ) {
+                                if ( isset( $t->rewrite['hierarchical'] ) && $t->rewrite['hierarchical'] ) {
                                         $q[$t->query_var] = wp_basename( $q[$t->query_var] );
                                 }