IOException on compilation (filename too long).

The following is fine:

``` scala
  case class X(ys: List[Int])
  println(X(List(1,2,3)).pickle)

  case class X2345(ys: List[Int])
  println(X2345(List(1,2,3)).pickle)
```

When I add this line, I get a 658-line long compile-time exception:

``` scala
  case class X2345678(ys: List[Int])
  println(X2345678(List(1,2,3)).pickle)
```

error log: https://gist.github.com/Synesso/e2d39de5be20e7f302be
