taxonomy_term_path returns bad alias

In some cases, calling taxonomy_term_path seems to return the wrong path. This line #478 in site_map.module:

$term_item .= l($term->name, ($cat_depth < 0) ? taxonomy_term_path($term) : "taxonomy/term/$term->tid/$cat_depth", array('attributes' => array('title' => $term-> description)));

could be simplified to:

$term_item .= l($term->name, ($cat_depth < 0) ? "taxonomy/term/$term->tid" : "taxonomy/term/$term->tid/$cat_depth", array('attributes' => array('title' => $term-> description)));

to avoid the bad path alias problem. Somehow, taxonomy term path is, for certain vocabularies, adding the domain name and / to the path. So, you end up with a path like http://www.drupal.org/www.drupal.org/someterm-path-alias. It only happens when I set the path depth setting to -1 in the sitemap config. It doesn't happen for all of my vocabs either, just the one that is not multiple select and only has one content type assigned. Very strange.