For real. If its not acting the same, then its not the same thing, give it a different name and release your 0.1. I guess maybe we run out of namespace with this methodology? Suddenly we end up with software named axsladkjfaksldjf, and then hackers start camping on axsladejfaksldjf

The name space is not a problem, in my opinion. If you have a library sdaffj, and you want to release a new, incompatible version, release it under the name sdaffj2, next incompatible version under name sdaffj3, etc.