Ticket #10930: classes.patch

wp-includes/classes.php

@@ -470 +470 @@
                         status_header( 404 );
                         nocache_headers();
                 } elseif ( !is_404() ) {
-                        status_header( 200 );
+                        if ( $wp_query->is_singular && count($wp_query->posts) == 0 ) {
+                                $wp_query->set_404();
+                                status_header( 404 );
+                                nocache_headers();
+                        } else {
+                                status_header( 200 );   
+                        }
                 }
         }