2 byte Tag names don’t show up in WP 2.6

The code below seems to return empty string when the Tag Name is in 2 byte characters and tag slug is like this(for example): %e3%82%a2%e3%83%a1%e3%83%aa%e3%82%ab.

<?php single_tag_title(); ?>

In WP 2.5.1, it has been functioning correctly.