Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.585.2.19
diff -u -p -r1.585.2.19 system.module
--- modules/system/system.module	5 Sep 2008 09:29:23 -0000	1.585.2.19
+++ modules/system/system.module	14 Sep 2008 18:34:10 -0000
@@ -1874,6 +1874,12 @@ function _system_zonelist() {
  *  and contains the same output as if called via the menu system.
  */
 function system_check_http_request() {
+  // This variable can be set in settings.php to bypass the check when it is
+  // known to fail (site behind HTTP authentication or SSL, etc.).
+  if (variable_get('assume_http_request_works', FALSE)) {
+    variable_set('drupal_http_request_fails', FALSE);
+    return TRUE;
+  }
   // Check whether we can do any request at all. First get the results for
   // a very simple page which has access TRUE set via the menu system. Then,
   // try to drupal_http_request() the same page and compare.