Index: wp-admin/includes/user.php
===================================================================
--- wp-admin/includes/user.php	(revision 21514)
+++ wp-admin/includes/user.php	(working copy)
@@ -331,7 +331,7 @@
 	if ( ! get_user_option('default_password_nag', $user_ID) ) //Short circuit it.
 		return;
 
-	$new_data = get_userdata($user_ID);
+	$new_data = new WP_User($user_ID);
 
 	if ( $new_data->user_pass != $old_data->user_pass ) { //Remove the nag if the password has been changed.
 		delete_user_setting('default_password_nag', $user_ID);
Index: wp-includes/pluggable.php
===================================================================
--- wp-includes/pluggable.php	(revision 21514)
+++ wp-includes/pluggable.php	(working copy)
@@ -579,7 +579,7 @@
  * @return string Authentication cookie contents
  */
 function wp_generate_auth_cookie($user_id, $expiration, $scheme = 'auth') {
-	$user = get_userdata($user_id);
+	$user = new WP_User($user_id);
 
 	$pass_frag = substr($user->user_pass, 8, 4);