[FrameworkBundle] Fix format parsing

src/Symfony/Bundle/FrameworkBundle/Templating/Engine.php

@@ -167,7 +167,7 @@ class Engine extends BaseEngine
         $elements = explode('.', $parts[2]);
         if (3 === count($elements)) {
             $parts[2] = $elements[0];
-            $options['format'] = $elements[1];
+            $options['format'] = '.'.$elements[1];
             $options['renderer'] = $elements[2];
         } elseif (2 === count($elements)) {
             $parts[2] = $elements[0];