Many people have had fingers pointed at them, but it is not really interesting who made the mistake: everyone makes mistakes. What's interesting is the situation that encouraged making the mistake and that made it possible not to notice it for almost two years.
Read it here
I've spent a lot of the past decade maintaining both Plan 9 and a port of the Plan 9 software to Unix. I've edited a lot of code I didn't fully understand, and I've answered questions about code that I did understand when other people came asking. I've made my share of embarrassing mistakes editing unfamiliar code, and I've probably given my share of unintentionally wrong advice. Even the best programmers are always going to make mistakes. The lessons of the fiasco, for me, are the steps that can be taken to make the mistakes less frequent and easier to find.