backed out 648b42a75739, which was a NON-trivial whitespace commit.  It broke the Typography class's string replacements, for instance
diff --git a/system/helpers/security_helper.php b/system/helpers/security_helper.php
index a4df656..678dac8 100644
--- a/system/helpers/security_helper.php
+++ b/system/helpers/security_helper.php
@@ -1,4 +1,4 @@
-<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
 /**
  * CodeIgniter
  *
@@ -119,7 +119,7 @@
 {
 	function encode_php_tags($str)
 	{
-		return str_replace(array('<?php', '<?PHP', '<?', '?>'), array('&lt;?php', '&lt;?PHP', '&lt;?', '?&gt;'), $str);
+		return str_replace(array('<?php', '<?PHP', '<?', '?>'),  array('&lt;?php', '&lt;?PHP', '&lt;?', '?&gt;'), $str);
 	}
 }