Added comment explaining nonobvious self.__dict__ assignment in django.conf.__init__.py

    def __setattr__(self, name, value):

        if name == '_target':

            # Assign directly to self.__dict__, because otherwise we'd call

            # __setattr__(), which would be an infinite loop.

            self.__dict__['_target'] = value

        else:

            setattr(self._target, name, value)