A different fix to keep username.

htdocs/core/lib/security2.lib.php

@@ -210,7 +210,7 @@ function dol_loginfunction($langs,$conf,$mysoc)
 	$hookmanager->executeHooks('getLoginPageOptions',$parameters);    // Note that $action and $object may have been modified by some hooks
 
 	// Login
-	$login = (! empty($hookmanager->resArray['username']) ? $hookmanager->resArray['username'] : (GETPOST("username","alpha",2) ? GETPOST("username","alpha",2) : $demologin));
+	$login = (! empty($hookmanager->resArray['username']) ? $hookmanager->resArray['username'] : (GETPOST("username","alpha") ? GETPOST("username","alpha") : $demologin));
 	$password = $demopassword;
 
 	// Show logo (search in order: small company logo, large company logo, theme logo, common logo)