class wpdb get_results

As I’m writing a plugin, I saw in WP 2.3, in wp_db.php wpdb->get_results:

function get_results($query = null, $output = OBJECT)
...
		if ( $query )
			$this->query($query);
		else
			return null;

is this temporary or we are not allowed to pass null anymore in WP 2.3?