Issue #673020 follow-up by attiks: Critical fix to Content-Language HTTP header to not cause issues with Drush.

includes/bootstrap.inc

@@ -2498,7 +2498,6 @@ function get_t() {
  * Initialize all the defined language types.
  */
 function drupal_language_initialize() {
-  global $language;
   $types = language_types();
 
   // Ensure the language is correctly returned, even without multilanguage
@@ -2518,9 +2517,6 @@ function drupal_language_initialize() {
     // environments.
     bootstrap_invoke_all('language_init');
   }
-
-  // Send appropriate HTTP-Header for browsers and search engines.
-  header('Content-Language: ' . $language->language);
 }
 
 /**

includes/common.inc

@@ -2466,6 +2466,10 @@ function drupal_deliver_html_page($page_callback_result) {
     drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
   }
 
+  // Send appropriate HTTP-Header for browsers and search engines.
+  global $language;
+  drupal_add_http_header('Content-Language', $language->language);
+
   // Menu status constants are integers; page content is a string or array.
   if (is_int($page_callback_result)) {
     // @todo: Break these up into separate functions?