Where did the 'Dave Chappelle as writer' nonsense come from?

He's listed as a writer here and if you Google it you find a bunch of "check out all these awesome writers!" comments that lump him in with the others without anything to support it (they're presumably going off the erroneous IMDB listing) but I watched all 8 episodes last night and he's not credited in any of them, he doesn't appear in any of the sketches (other writers do, you'll see Louis CK and Dino in a few sketches, for example) and they don't talk about him in the extras and you would think they would because he's arguably more famous than anyone else involved in the show, including Carvey himself. They talk about Charlie Kaufman, Louis, Dino, etc. but not Chappelle.

As far as I'm concerned it's one of the many inaccuracies on IMDB but I'm kinda curious about where this rumor started because I can't find a shred of credible info to support it.