If Twitter is Ruby on Rails, Why Is There a PHP Session ID?

I was looking for CNN's main Twitter profile tonight so I typed it into Google and saw this weird URL:
twitter.com/cnn?PHPSESSID=55e3829a1bbc090475d430a754192e4b

I thought that Twitter was a Ruby on Rails app. It must be that someone (maybe CNN?) linked to a weird URL that had a PHPSESSID on it. Does anyone know the answer?