Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 19630)
+++ wp-includes/user.php	(working copy)
@@ -1398,6 +1398,10 @@
  * @return int The updated user's ID.
  */
 function wp_update_user($userdata) {
+	if ( isset( $userdata['data'] ) && is_object( $userdata['data'] ) ) {
+		$userdata = get_object_vars( $userdata['data'] );
+	}
+
 	$ID = (int) $userdata['ID'];
 
 	// First, get all of the original fields