In my application I would like to use the `item_lookup_field` setting for some of my resource endpoints. Also I need versioning.

In `settings.py` I have the following:

```
[...]
VERSIONING = True
ITEM_URL = 'regex("[a-z0-9]{0,24}")'
DOMAIN = {
    'people': {
        'item_lookup_field': 'lastname',
        'type': 'dict',
        'schema': {
            'firstname': { 'type': 'string' },
            'lastname': { 'type': 'string', 'required': True, 'unique': True },
        } 
    }
}

```

A `GET` on the enpoint `/people/obama` works, but `/people/obama?version=1` creates the following KeyError:

```
Traceback (most recent call last):
  File "/foobar/eve0.5_env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)

[...]

  File "/foobar/eve0.5_env/lib/python2.7/site-packages/Eve-0.5_dev-py2.7.egg/eve/methods/get.py", line 210, in getitem
resource, req, lookup, document, version)
  File "/foobar/eve0.5_env/lib/python2.7/site-packages/Eve-0.5_dev-py2.7.egg/eve/versioning.py", line 257, in get_old_document
    lookup[versioned_id_field()] = lookup[app.config['ID_FIELD']]
KeyError: '_id'

```

Do I need to change my configuration?

Is this a bug?

---

PS: first post, please tell me if you need anything else