Restoring protection measure when entering in main/install/

main/install/index.php

@@ -129,12 +129,12 @@ require_once __DIR__.'/version.php';
 
 // A protection measure for already installed systems.
 
-/*if (is_already_installed_system()) {
+if (is_already_installed_system()) {
 	// The system has already been installed, so block re-installation.
 	$global_error_code = 6;
 	require '../inc/global_error_message.inc.php';
 	die();
-}*/
+}
 
 /*		STEP 1 : INITIALIZES FORM VARIABLES IF IT IS THE FIRST VISIT */