Message 248424 - Python tracker

Looks fine to me.  IIRC, we moved the PyFloat_FromString implementation away from using Py_NAN in Python 3 for exactly this reason.

On this point, though:

> An aggressively optimizing compiler could treat 0 * x = 0 no matter what x is.

Wouldn't such a compiler be in violation of the C standard, at least if it defines __STDC_IEC_559__?