Ticket #38976: 38976.diff

src/wp-includes/rest-api.php

@@ -256 +256 @@
         $server = rest_get_server();
 
         // Fire off the request.
-        $server->serve_request( untrailingslashit( $GLOBALS['wp']->query_vars['rest_route'] ) );
+        $server->serve_request( '/' . trim( $GLOBALS['wp']->query_vars['rest_route'], '/' ) );
 
         // We're done.
         die();