>     Here's the Stack Overflow licensing policy:
>     Creative Commons CC-BY-SA

Also worth noting about Stack Overflow is that most people posting there
probably have no idea what license they are posting their code with.
I've been dealing with open source licenses for a decade and I've never
once remembered to think about the issue at all when posting something
there. Probably lots of people are in a similar position, not to mention
novice programmers. They don't clearly state the license in the UI when
you post, I don't know if it's stated anywhere except hidden deep in the
Terms and Conditions. But there have been big and well publicized
community discussions about it whenever it was changed.