Check for existence of the query var before switch(). Fixes a notice on Multisite users page.

git-svn-id: http://svn.automattic.com/wordpress/trunk@12906 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/user-new.php

@@ -113,7 +113,7 @@ wp_enqueue_script('password-strength-meter');
 
 require_once ('admin-header.php');
 
-if ( is_multisite() ) {
+if ( isset($_GET[ 'update' ]) && is_multisite() ) {
 	switch ( $_GET[ 'update' ] ) {
 		case "newuserconfimation":
 			$messages[] = '<div id="message" class="updated fade"><p>' . __('Invitation email sent to new user. A confirmation link must be clicked before their account is created.') . '</p></div>';