Replace a few require() uses with require_once() (should fix issue #1872)
diff --git a/system/core/CodeIgniter.php b/system/core/CodeIgniter.php
index 8159b19..f3592ea 100644
--- a/system/core/CodeIgniter.php
+++ b/system/core/CodeIgniter.php
@@ -50,7 +50,7 @@
  *  Load the global functions
  * ------------------------------------------------------
  */
-	require(BASEPATH.'core/Common.php');
+	require_once(BASEPATH.'core/Common.php');
 
 /*
  * ------------------------------------------------------