Corporate firewalls… never mind, that’s a rant for another day.
To appease the corporate firewalls for pip, create
with the following content:
[global] trusted-host = pypi.python.org pypi.org files.pythonhosted.org
http_proxy environment settings, and
away to your heart’s content.
Note that this solution works since pip 10.0, and yup, works at least within the corporate firewalls that I’m behind currently.