You're calling open() but never calling close(), which can lead to problems. An easy way to avoid leaving filehandles open is to use open as a [context manager](http://eigenhombre.com/2013/04/20/introduction-to-context-managers/), like so:
```python
with open(settings.MEDIA_ROOT + "/humans.txt", 'w') as target:
    HumansTXT().generate_file(target, repos)
```
The way that you're instantiating an object just to call a method is further evidence that the method should probably be a function instead.