Fix an escape_identifiers() bug
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index 39db161..dfaf0e0 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -1236,7 +1236,7 @@
 	 */
 	public function escape_identifiers($item)
 	{
-		if ($this->_escape_char === '' OR empty($item))
+		if ($this->_escape_char === '' OR empty($item) OR in_array($item, $this->_reserved_identifiers))
 		{
 			return $item;
 		}