Hello,
Recently a tiny working patch was posted to bug #787 [1].
The patch hasn't been merged yet and it would be great if it made it into TL2013.
Please remember to also close #746 [2] when the patch is merged.
Thanks,
Ismo Toijala
[1] http://tracker.luatex.org/view.php?id=787
[2] http://tracker.luatex.org/view.php?id=746