haddock: panic! (the 'impossible' happened)

After running "cabal install yi", I got this message:

dist/build/tmp-79484/src/library/Yi/Eval.hs:139:5: Warning:
    Defined but not used: `publishedActions_'
  73% ( 11 / 15) in 'Yi.Eval'
  19% (  5 / 26) in 'Yi.Modes'
  25% (  1 /  4) in 'Yi.Mode.IReader'
   0% (  0 /  2) in 'Yi.Mode.Compilation'
  33% (  1 /  3) in 'Yi.Mode.JavaScript'
  50% (  2 /  4) in 'Yi.Mode.Latex'
  31% (  4 / 13) in 'Yi.Mode.Interactive'
  60% (  9 / 15) in 'Yi.Command'
  58% ( 15 / 26) in 'Yi.Keymap.Emacs.Utils'
haddock: panic! (the 'impossible' happened)
  (GHC version 7.6.3 for x86_64-apple-darwin):
	mkWWcpr: not a product
<<details unavailable>>

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

Installing library in /Users/diegos/Library/Haskell/ghc-7.6.3/lib/yi-0.8.1/lib
Installing executable(s) in
/Users/diegos/Library/Haskell/ghc-7.6.3/lib/yi-0.8.1/bin
Registering yi-0.8.1...
Installed yi-0.8.1

I'm on OS 10.9.3, GHC 7.6.3.

Please let me know if I can provide any other info that could be helpful, or if a full output would help.

Thanks, Diego Saa