So, the bug is: that there happens to be some code in there, accidentally one must assume, that is able to modify your contacts, specifically by doing a search and replace of email addresses. Erm, sorry.. how did code like that get in there by accident? Or if we assume the code is there on purpose but this is a bug in that code, then for what purpose is that code in there in the first place? Why do you want to mess with my contacts?
Or are you just spouting bollocks Mr Zuckerberg?
See, they know that it'll take a lot to make people stop using Facebook, since for many of us it has become something we like and use a lot, despite our better judgement. So they feel they can just do what they like and we'll put up with it. And apparently they can all sleep at night and live with the fact that they're devious, lying, morally repugnant pieces of slime.
I'm going now to post that on my wall.