[-] BO : Retro compat, PS_ADMIN_DIR not defined

admin-dev/index.php

@@ -27,6 +27,9 @@
 $timer_start = microtime(true);
 define('_PS_ADMIN_DIR_', getcwd());
 
+if (!defined('PS_ADMIN_DIR'))
+	define('PS_ADMIN_DIR', PS_ADMIN_DIR);
+
 require(_PS_ADMIN_DIR_.'/../config/config.inc.php');
 require(_PS_ADMIN_DIR_.'/functions.php');