TypeInType Compile-time Panic

I've been playing around with GHC 8.0.1-rc4 release and got a panic from the following (stripped down) code:

{-# LANGUAGE TypeInType #-}

data Nat = Z | S Nat

class C (n :: Nat) where
  type T n :: Nat
  f :: (a :: T n)

ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.0.20160421 for x86_64-apple-darwin):
	isInjectiveTyCon sees a TcTyCon T

Trac metadata

Trac field	Value
Version	8.0.1-rc4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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