Index: includes/file.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/file.inc,v
retrieving revision 1.243
diff -u -p -r1.243 file.inc
--- includes/file.inc	15 Dec 2010 03:39:41 -0000	1.243
+++ includes/file.inc	20 Feb 2011 22:55:00 -0000
@@ -202,9 +202,8 @@ function file_stream_wrapper_get_class($
  * @see file_uri_target()
  */
 function file_uri_scheme($uri) {
-  $data = explode('://', $uri, 2);
-
-  return count($data) == 2 ? $data[0] : FALSE;
+  $position = strpos($uri, '://');
+  return $position ? substr($uri, 0, $position) : FALSE;
 }
 
 /**