Datepicker not positioned for only-child hidden inputs

When a datepicker is applied to a hidden input, datepicker._findPos() tries to seek for the next visible sibling. If there are no siblings, it fails.

Pseudocode example:

<div><input id="date-me" type="hidden datepicker">Asdf</div>
<script>
$('#date-me').datepicker();
</script>

Yields a non-positioned datepicker. I've patched this on my Github fork. As soon as I get a ticket ID here, I'll post a link.