Fixed in https://hg.python.org/peps/rev/7ad183c1d9be

I'll quote the commit message here:

    pep-492: Update benchmark code

    Since coroutines now have a distinct type, they do not support
    iteration. Instead of doing 'list(o)', we now do 'o.send(None)'
    until StopIteration.

    Note, that the updated timings are due to the difference of
    doing a loop in Python vs doing it in C ('list()' vs 'while True').

Marcin and Terry, thanks for reporting this!