Comment 4 for bug 1686111

Steps to reproduce:

```
mkdir simplepkg/src/simplepkg
cd simplepkg
git init
```

src/simplepkg/__init__.py:
```
print("Hello, world!")
```

setup.py:
```
#!/usr/bin/env python

from setuptools import setup

setup(
    setup_requires=['pbr'],
    pbr=True,
)
```

setup.cfg:

```
[metadata]
name = simplepkg

[files]
packages_root = src/
packages =
    simplepkg
```

Create virtualenv and install our package:

```
python -m venv env
source env/bin/activate
pip install .
python -c 'import simplepkg'
```

The output is:

```
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'simplepkg'
```