LearnBoost/mongoose — pull request #1517 by zedgu (2013-05-31 17:09:05+00:00)
Title: Just found a little bug.

if schema like this:
```javascript
_id: {
type: Buffer,
default: function() {
return (new MongooseBuffer(uuid.v4())).toObject(0x04);
}
}
```
the sub_type will be lost.

And I think I really need the spec that Heckmann has mentioned before >> https://github.com/LearnBoost/mongoose/pull/1000#issuecomment-6912708