https://github.com/python/cpython/pull/1426 implements the blacklist option.

I chose the conservative approach: hope that poll() will be fixed in 16.6.x. The problem of this approach is that test_asyncore and test_eintr will fail again if Apple doesn't fix poll().

Since I would like to backport this fix in 2.7, 3.5 and 3.6 and not have to modify the code at each broken macOS release, maybe we can use the pessimistic solution: blacklist Darwin >= 16.x, and only start again to whitelist once Apple releases a fixed macOS.