title: "Unresolved import" for Python package installed using setup.py
body: <p>I'm receiving a "[Python] Unresolved import.." error for a custom package that I have installed with <code>python setup.py install</code>. If I instead install the package with <code>pip</code> by running <code>python setup.py sdist</code> and then running <code>pip install &lt;package.tar.gz&gt;</code> the error goes away, and I cannot figure out why. I am running all of this within the same virtualenv, and I have made sure that VS Code is correctly using this virtualenv as the source interpreter (this is Python 3.7). Although I could find a workaround here, <code>pip install</code> is not always available. Any thoughts?</p>