tryTakeMVar fails

[Simon Marlow]

> This program crashes on ghc 5.02, on my RH7.1
> 
> module Main where
> 
> import MVar
> 
> main = 
>  do { mVar <- newMVar True
>     ; tryTakeMVar mVar
>     ; return ()
>     }

Darn.  tryTakeMVar is busted in 5.02 I'm afraid.  I've just fixed it in
the HEAD, maybe 5.02.3 will have it fixed if we do another release along
that branch.

Cheers,
	Simon