Bugs happen. Even stupid oh-my-god-i-can't-believe-i-did-that bugs happen. And they happen to the best of us.
However, when someone reports a vulnerability about my code to me or I discover a problem myself, the very first thing I do is break out the grep. I grep the shit out of my code. Because I am a human being. I am a creature of habit. And if I screwed up in one place, I promise you, I did it in other places too.
The problem? Github didn't do that. At least, that's the impression from the information coming out. The guy reported the issue on Friday, they fixed that specific instance of the issue ... and it remained a problem in other places. That is unacceptable and unprofessional. They should have burned the midnight oil and made sure the same problem wasn't prevalent in other parts of the code.
Having said that, I am a loyal Github client and will remain so. Every service provider I use gets a once-a-year-screw-up credit. Github just used theirs. Switching because of one incident is premature and will be sure to cause regrets.