please update multi line identation. ....

just a minor comment. Instead of:

```
request = manufacture.makeTwistedWebRequest()

self.assertIsNone(json_rpc._get_session(request))
```

I prefer

```
request = manufacture.makeTwistedWebRequest()

session = json_rpc._get_session(request)

self.assertIsNone(session)
```

Also, instead of "recycling" the request, it is preferred to create a new one... just to avoid side effects. 

For this test should not be a big problem.