Ticket #21228: query-by-tt_id.patch

wp-includes/taxonomy.php

@@ -784 +784 @@
                                         AND $wpdb->terms.{$query['field']} IN ($terms)
                                 " );
                                 break;
-
+                        case 'term_taxonomy_id':
+                                $terms = implode( ',', array_map( 'intval', $query['terms'] ) );
+                                $terms = $wpdb->get_col( "
+                                        SELECT $resulting_field
+                                        FROM $wpdb->term_taxonomy
+                                        WHERE term_taxonomy_id IN ($terms)
+                                " );
+                                break;
                         default:
                                 $terms = implode( ',', array_map( 'intval', $query['terms'] ) );
                                 $terms = $wpdb->get_col( "