It's a strange loop, actually. The requiring attribution would be more restrictive, since the current license does not require attribution. If you re-license it with a license that does not require a less restrictive license, and then license it again with a license that is more restrictive, then you've violated the original one.
Logically, it implies "You can only release it under this license".
That is, the license says, "This is obvious, and doesn't need a license", and is a joke.
