New __getattr__ definition

dbref.py

# New __getattr__ definition for bson/dbref.py to support pickling

def __getattr__(self, key):
    # checking for the mangled name. ugly.
    if '_DBRef__kwargs' in self.__dict__:
        try:
            return self.__kwargs[key]
        except KeyError:
            pass

    raise AttributeError("'{0}' object has no attribute '{1}'".format(
        self.__class__.__name__, key
    ))