External Core bug: "Illegal data constructor name"

If you compile the "lambda" nofib benchmark with -fext-core, GHC won't
compile the resulting .hcr file:

[krc@lagaffe lambda]$ ghc -fext-core Main.hs
[krc@lagaffe lambda]$ ghc Main.hcr

Illegal data constructor name `Main.StateMonad2'

This is using GHC 5.05.

-- 
Kirsten Chevalier * krc@xxxxxxxxxxxxxxxxxxx * Often in error, never in doubt