Is nan in (nan,) correct?

[random832 at fastmail.us]

On Thu, Mar 5, 2015, at 22:49, Chris Angelico wrote:
> I'm not sure it's just an optimization. Compare this post from
> python-dev, where Nick Coghlan discusses the same topic:
> 
> https://mail.python.org/pipermail/python-dev/2014-July/135476.html

If it is a bug for NaN to "infect" containers' behavior, we need to take
a serious look at sort().