I really doubt Warp and RDJ have anything other than a very relaxed contract or agreement. I don't think RDJ likes any control at all over his work, and Warp probably provide the distribution and marketing and not much else, and Rich is probably very happy with that if he still releases through them/Bleep. It's not like Rich is going to need much cash to cover mastering (does he do that stuff himself? I forget), and he has his own studio to work and record in, so with Warp providing very little, they can't demand very much back.
Contracts come in all different "shapes and sizes" so there is no need to assume Warp hold rights over his work, it could just be the distribution/marketing of it.
edit: That being said, they're probably missing out on a lot of dosh, but probably not much they can do about it.
The "Barry's Bangers" splattering of the google docs a couple of days ago claimed CCAI was a contract breaker, which seems to match with an interview given years ago about how after 'Drukqs' he had 2 albums to go on his Warp contract (if my memory serves me at all, which is debatable.)