How to fix the pip9.exceptions.InstallationError

Make sure the version of your pip and setuptools is sufficient for manylinux2014 wheels.

A) System Install

sudo python3 -m pip install -U pip
sudo python3 -m pip install -U setuptools

B) Virtual Env / Pipenv

# Within the venv
pip3 install -U pip
pip3 install -U setuptools

Explanation

For me, python setup.py egg_info probably failed because of a recent change in python wheels, as manylinux1 wheels were replaced by manylinux2014 wheels according to open-cv faq.