--- /Users/gustavobordoni/workspace/edg-wordpress/sites/blogs/wp-includes/post.php	2012-03-11 23:34:04.000000000 -0300
+++ /Users/gustavobordoni/tmp/post.php	2012-03-11 23:34:42.000000000 -0300
@@ -5183,8 +5183,7 @@
 	if ( $post && $thumbnail_id && get_post( $thumbnail_id ) ) {
 		$thumbnail_html = wp_get_attachment_image( $thumbnail_id, 'thumbnail' );
 		if ( ! empty( $thumbnail_html ) ) {
-			update_post_meta( $post->ID, '_thumbnail_id', $thumbnail_id );
-			return true;
+			return update_post_meta( $post->ID, '_thumbnail_id', $thumbnail_id );
 		}
 	}
 	return false;