Regression in Scala 2.10 concerning self types

  trait TFn1B {
    type In
    type Out
    type Apply[T <: In] <: Out
  }

  trait TFn1[I, O] extends TFn1B {
    type In = I
    type Out = O
  }

  trait >>[F1 <: TFn1[_, _], F2 <: TFn1[_, _]] extends TFn1[F1#In, F2#Out] {
    type Apply[T] = F2#Apply[F1#Apply[T]]
  }

In 2.10 the compiler complains:

Fun.scala:12: error: illegal inheritance;
 self-type this.>>[F1,F2] does not conform to this.TFn1[_$1,_$4]'s selftype this.TFn1[_$1,_$4]
  trait >>[F1 <: TFn1[_, _], F2 <: TFn1[_, _]] extends TFn1[F1#In, F2#Out] {
                                                       ^
one error found

Should I file a bug or is this expected?

Thanks and bye,

Simon