Weird, somehow extra characters are being added to the end of that url. Removing the trailing / fixes it.
http://www.theonion.com/articles/the-onion-urges-barack-obam...
http://www.theonion.com/articles/the-onion-urges-barack-obam...
Thanks, fixed. Looks like HN is over-escaping some values -- click the 'link' link to this post and see how the first line is over-escaped in the title bar?