Ticket #35666: 35666.4.diff

src/wp-includes/functions.php

@@ -2868 +2868 @@
         );
         $r = wp_parse_args( $args, $defaults );
 
-        if ( ! headers_sent() ) {
+        if ( ! headers_sent() && ( 0 === ob_get_level() || 0 === ob_get_length() ) ) {
                 status_header( $r['response'] );
         }
         if ( is_scalar( $message ) )