GHC 6.1 TH panic!

$ ghci -package haskell-src -fglasgow-exts
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 6.1, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Loading package haskell-src ... linking ... done.
Prelude> runQ [| 20# |] >>= print

<interactive>:1: Variable not in scope: `runQ'
Prelude> :m Language.Haskell.THSyntax
Prelude Language.Haskell.THSyntax> runQ [| 20# |] >>= print
LitExp (IntPrimLit 20)
Prelude Language.Haskell.THSyntax> let decl = reifyDecl head
c:\lang\ghc\bin\ghc.exe: panic! (the `impossible' happened, GHC version
6.1):
        dsReify reifyDecl GHCziList.head {- v r1xG -}

Please report it as a compiler bug to glasgow-haskell-bugs@xxxxxxxxxxx,
or http://sourceforge.net/projects/ghc/.