pytorch-lightning: Install within conda env breaks

Describe the bug Installation inside conda environment fails on Mac and Linux with the following message

    ERROR: Command errored out with exit status 1:
     command: /Users/dsuess/Library/Conda/envs/test/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/ky/6gq9n6md77n0y3hsf37_b6qr0000gn/T/pip-install-8izjxcqp/pytorch-lightning/setup.py'"'"'; __file__='"'"'/private/var/folders/ky/6gq9n6md77n0y3hsf37_b6qr0000gn/T/pip-install-8izjxcqp/pytorch-lightning/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base pip-egg-info
         cwd: /private/var/folders/ky/6gq9n6md77n0y3hsf37_b6qr0000gn/T/pip-install-8izjxcqp/pytorch-lightning/
    Complete output (3 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
    ModuleNotFoundError: No module named 'setuptools'
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

Running python -c 'import setuptools' does not fail, so setuptools is installed. Also, installing directly from github is fine. I think it’s due to the site directory inside the tarball from pypi breaking python

To Reproduce

conda create --name test python=3
conda activate test
python -m pip install pytorch-lightning

Expected behavior The package should be installed succesfully

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: MacOS 10.14.6 and Ubuntu 18.04
• conda 4.7.11
• pip 19.2.3