Ticket #16152: 16152.3.patch

wp-includes/query.php

@@ -1684 +1684 @@
                                 $cat = abs($cat);
                                 if ( $in ) {
                                         $q['category__in'][] = $cat;
+                                        $q['category__in'] = array_merge( $q['category__in'], get_term_children($cat, 'category') );
                                 } else {
                                         $q['category__not_in'][] = $cat;
+                                        $q['category__not_in'] = array_merge( $q['category__not_in'], get_term_children($cat, 'category') );
                                 }
                         }
                         $q['cat'] = implode(',', $req_cats);
                 }
 
                 if ( !empty($q['category__in']) ) {
-                        $q['category__in'] = array_unique( $q['category__in'] );
+                        $q['category__in'] = array_unique( (array) $q['category__in'] );
                         $tax_query[] = array(
                                 'taxonomy' => 'category',
                                 'terms' => $q['category__in'],
-                                'field' => 'term_id'
+                                'field' => 'term_id',
+                                'include_children' => false
                         );
                 }
 
                 if ( !empty($q['category__not_in']) ) {
-                        $q['category__not_in'] = array_unique( $q['category__not_in'] );
+                        $q['category__not_in'] = array_unique( (array) $q['category__not_in'] );
                         $tax_query[] = array(
                                 'taxonomy' => 'category',
                                 'terms' => $q['category__not_in'],
                                 'operator' => 'NOT IN',
+                                'include_children' => false
                         );
                 }