Ticket #12668: 12668-widgets.patch

src/wp-includes/default-widgets.php

@@ -856 +856 @@
                 $comments = get_comments( apply_filters( 'widget_comments_args', array(
                         'number'      => $number,
                         'status'      => 'approve',
-                        'post_status' => 'publish'
+                        'post_status' => 'publish',
+                        'type'        => array( 'pingback', 'trackback', 'comment' )
                 ) ) );
 
                 $output .= $args['before_widget'];