Cannot install pandas correctly due to unreachable code
After running python setup.py build_ext --inplace -j 0:

![Screenshot 2020-03-21 at 12 26 39](https://user-images.githubusercontent.com/24496267/77225440-4b793d00-6b6f-11ea-8267-95496c9d273c.png)



MacOS 10.14
python 3.6.6

I tried to install pandas from source in a setup virtual environment using pip.
I cloned the repository, created the virtual environment with python -m venv.
I ran pip install -r requirements-dev.txt
Had a few problems with versions of dependencies being too recent and not satisfying requirements, but I manually downgraded them.
And when I ran the above "python setup.py build_ext --inplace -j 0" I got the issue mentioned.

Thanks for your help