Well, you'd want them to try to crawl it. Perhaps there was a bot crawling their site for such links and they wanted to identify specifically that one. It seems

Well, you'd want them to try to crawl it. Perhaps there was a bot crawling their site for such links and they wanted to identify specifically that one. It seems most likely that such URL's never existed, but this would be a decent way to identify a bot that's otherwise not distinguishable.