Impossible happened while compiling the lunabot

[Ahn, Ki Yung]

kyagrd at kyavaio:~/tmp/lunabot$ which ghc
/usr/bin/ghc
kyagrd at kyavaio:~/tmp/lunabot$ uname -a
Linux kyavaio 2.6.29-2-686 #1 SMP Sun May 17 17:56:29 UTC 2009 i686
GNU/Linux
kyagrd at kyavaio:~/tmp$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.10.4
kyagrd at kyavaio:~/tmp$ darcs get http://moonpatio.com/repos/lunabot
kyagrd at kyavaio:~/tmp$ cd lunabot
kyagrd at kyavaio:~/tmp/lunabot$ cabal install haskell-src-meta vacuum
...
kyagrd at kyavaio:~/tmp/lunabot$ cabal build
Preprocessing library lunabot-0.9.9...
Building lunabot-0.9.9...
[3 of 5] Compiling Luna.Bot.Eval.PackageConf (
Luna/Bot/Eval/PackageConf.hs, dist/build/Luna/Bot/Eval/PackageConf.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 6.10.4 for i386-unknown-linux):
	No match in record selector Var.tcTyVarDetails

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug