kennethreitz/requests — pull request #1503 by skastel (2013-07-29 20:39:42+00:00)
Title: Fixing error return to be consistent with tuple return at the end of the method

In passing I managed to produce a situation where I would get an error when this check fails. When this gets called on line 391:

```python
391 # Multi-part file uploads.
392 if files:
393 (body, content_type) = self._encode_files(files, data)
```

Which would result in:
```TypeError: 'NoneType' object is not iterable```

This patch fixes that return.