BSON type 0x0c (DBPointer) is deprecated, but it should still be deserializable.

By comparison, the Python driver automatically converts DBPointers to DBRefs and re-serializes them as such, since any DBPointer can be represented by a DBRef. This particular behavior is not required by any specification, but it is convenient. Being able to deserialize DBPointer to anything at all is required for reading documents that contain DBPointer without raising an error (which in turn requires the user to specify a projection in order to extract any other fields).