Fix: use $conf->entity if defined

htdocs/main.inc.php

@@ -374,7 +374,7 @@ if (! defined('NOLOGIN'))
 
         $usertotest		= (! empty($_COOKIE['login_dolibarr']) ? $_COOKIE['login_dolibarr'] : GETPOST("username","alpha",2));
         $passwordtotest	= (! empty($_COOKIE['password_dolibarr']) ? $_COOKIE['password_dolibarr'] : GETPOST('password'));
-        $entitytotest	= (GETPOST('entity','int') ? GETPOST('entity','int') : 1);
+        $entitytotest	= (GETPOST('entity','int') ? GETPOST('entity','int') : (!empty($conf->entity) ? $conf->entity : 1));
 
         // Validation of login/pass/entity
         // If ok, the variable login will be returned