Looks like Bit.ly's security measures are kicking in against rival cli.gs's short URLs.
It's not all that rare to get URL shorteners stacking on top of one an other; you just don't tend to notice when it happens.
This sort of stacking is commonly caused when a Twitter desktop client, set to use a tracking URL shortener, is used to fire off a retweet.
This screen grab shows what happens when Bit.ly is asked to redirect to Cli.gs. If you're curious the URL that the cli.gs points to is Flickr.com and to a picture of bigmouthmedia's Bjørnis.