[Haskell-cafe] Problem while compiling ghc 6.8

Hi, I got my ghc 6.8 by `darcs get --partial http://darcs.haskell.org/ghc-6.8/ghc`, and after `darcs-all get`, `sh boot`, `configure`, without any problem, I started to make it. Well, when compiling libraries/stm, it reports "Control/Concurrent/STM/TVar.hs:22:8: Not in scope: `readTVarIO'. I tried to reget the source without '--partial', still the same.