Ticket #25151: 25151.patch

src/wp-includes/comment-template.php

@@ -1606 +1606 @@
         $user = wp_get_current_user();
         $user_identity = $user->exists() ? $user->display_name : '';
 
+        $args = wp_parse_args( $args );
         if ( ! isset( $args['format'] ) )
                 $args['format'] = current_theme_supports( 'html5', 'comment-form' ) ? 'html5' : 'xhtml';