Hi, new version 3.9.1 not install pytest.py file when egg install from setuptools tests_require parameter is used.

I have this argument in setup.py setup function:

tests_require=['pytest'],

Then when i run python3 setup.py test and no pytest is installed in system yet, then setuptools install all packages, and it's dependencies to .egg directory. So:

~$ ls .eggs/pytest-3.9.1-py3.5.egg/
EGG-INFO  _pytest
~$ ls .eggs/pytest-3.8.2-py3.5.egg/
EGG-INFO  __pycache__  _pytest	pytest.py

Somewhere in my test setup class i import pytest, which not exist now. When pytest is installed via pip3, pytest.py exist in filesystem, for example at /usr/local/lib/python3.5/dist-packages/pytest.py.

Here is my pip3 list

Click (7.0)
extendparser (0.2.0)
Flask (1.0.2)
gevent (1.3.7)
greenlet (0.4.15)
itsdangerous (0.24)
Jinja2 (2.10)
Jinja2-template-info (0.1.1)
jsonschema (2.6.0)
lazy-object-proxy (1.3.1)
MarkupSafe (1.0)
openapi-core (0.6.0)
openapi-spec-validator (0.2.4)
pip (9.0.1)
prometheus-client (0.4.2)
PyYAML (3.13)
setuptools (33.1.1)
six (1.11.0)
uWSGI (2.0.17.1)
Werkzeug (0.14.1)
wheel (0.29.0)

I use that on updated debian stretch docker image with python3 3.5.3-1 package.