This problem seems to be mistaken, black can't kill white as far as we can see.
unkx80: lives. It does not matter if is exchanged with . The thing is, (1) if later Black plays at , then White simply captures at a and we get a bent four in the corner with two external liberties, which lives, and (2) any other move by Black cannot reduce White's two external liberties, and so cannot prevent White from living by oshitsubushi at a.
maruseru: Yes, after I edited the page and before I just got back, I thought about the problem some more and your occurred to me as well. Thanks for the clarification.
After 9, a-k (j connects left of 1). This is an unfavourable ko in which if White loses the ko she gets to play three times elsewhere.
I was lucky to be able to show this to FanHui on KGS. He didn't say there were any mistakes in these variations. So I guess the conclusion is that this is another errata.