Rely on upstream package to supply typing and challenge-bypass-ristretto as
necessary.  Simplify our expression (approximately pointfree style) so we
don't have to know about any other arguments that might be passed or accepted.

At least, I suppose it was incorrect.  It won't build anywhere it has not
already built.  I don't know how it built where it already built.

why make it a plugin, then, you may ask.
or perhaps you may not ask.

overrides

They're not necessary on newly selected nixpkgs revision.

The layer above will have to make sure that it is.