Fixed guessing a template info for exceptions

lib/Twig/Error.php

@@ -229,6 +229,8 @@ class Twig_Error extends Exception
 
         while ($e = array_pop($exceptions)) {
             $traces = $e->getTrace();
+            array_unshift($traces, array('file' => $e->getFile(), 'line' => $e->getLine()));
+
             while ($trace = array_shift($traces)) {
                 if (!isset($trace['file']) || !isset($trace['line']) || $file != $trace['file']) {
                     continue;

test/Twig/Tests/Fixtures/exceptions/undefined_trait.test

@@ -6,4 +6,4 @@ Exception for an undefined trait
 {% block bar %}
 {% endblock %}
 --EXCEPTION--
-Twig_Error_Runtime: Block "foobar" is not defined in trait "foo" in "index.twig".
+Twig_Error_Runtime: Block "foobar" is not defined in trait "foo" in "index.twig" at line 2.