Requirements.txt fails while installing knitlibs from pip

```
(venv) $ pip install -r requirements.txt
Collecting Flask (from -r requirements.txt (line 1))
Collecting flask-cors (from -r requirements.txt (line 2))
Downloading Flask-Cors-2.1.2.tar.gz
Collecting knitlib (from -r requirements.txt (line 3))
Could not find a version that satisfies the requirement knitlib (from -r requirements.txt (line 3)) (from versions: )
No matching distribution found for knitlib (from -r requirements.txt (line 3))
You are using pip version 8.0.2, however version 8.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
```

Start by inspecting requirements.txt, especially line 3, and reproduce the failure with pip install -r requirements.txt. Check why knitlib cannot be resolved from the listed requirements; done means the requirements file installs successfully without the reported knitlib error.

Written by the indexing model from the issue text.