Merge branch '4.1' into 4.2

* 4.1:
  the string "0" is a valid service identifier
  remove unreachable code
  updated MimeType extensions

Author: fabpot

Tests/Node/TransNodeTest.php

@@ -49,12 +49,8 @@ protected function getVariableGetterWithoutStrictCheck($name)
 
     protected function getVariableGetterWithStrictCheck($name)
     {
-        if (Environment::VERSION_ID > 20404) {
-            return sprintf('(isset($context["%s"]) || array_key_exists("%1$s", $context) ? $context["%1$s"] : (function () { throw new Twig_Error_Runtime(\'Variable "%1$s" does not exist.\', 0, $this->source); })())', $name);
-        }
-
         if (Environment::MAJOR_VERSION >= 2) {
-            return sprintf('(isset($context["%s"]) || array_key_exists("%1$s", $context) ? $context["%1$s"] : (function () { throw new Twig_Error_Runtime(\'Variable "%1$s" does not exist.\', 0, $this->getSourceContext()); })())', $name);
+            return sprintf('(isset($context["%s"]) || array_key_exists("%1$s", $context) ? $context["%1$s"] : (function () { throw new Twig_Error_Runtime(\'Variable "%1$s" does not exist.\', 0, $this->source); })())', $name);
         }
 
         return sprintf('($context["%s"] ?? $this->getContext($context, "%1$s"))', $name);