Comment by Athas

This is the C explanation perspective, but a similar thing could happen in Python, if you write `s[0]` instead of `s`, perhaps due to a refactoring that changes an array of keys to a single key. This is because Python does not distinguish characters from strings. (Not an indictment of Python; just another proposal for how this could happen, and I would say it is more likely to use Python than C in some hacked-up signing script.)