#327551: Problem in Drupal 6? by zvikico - Fixed messages that display when submitting the taxonomy redirect form so that only appropriate messages display.
The format of redirects has changed to replace !tid and !name with the term id and term name in paths. Run update.php to update your old paths to the new format.
You can now override the redirection by defining the function taxonomy_redirect_custom_term_path($term, $path)