non-uniform treatment of Nothing continues to bother

[scabug]

scala> implicitly[Manifest[List[String]]]
res15: Manifest[List[String]] = scala.collection.immutable.List[java.lang.String]

scala> implicitly[Manifest[List[Nothing]]]
res16: Manifest[List[Nothing]] = scala.collection.immutable.List[Nothing]

scala> def f[T, M[_]](x: M[T])(implicit m: Manifest[M[T]]) = m
f: [T, M[_]](x: M[T])(implicit m: Manifest[M[T]])Manifest[M[T]]

scala> f(List[String]())
res18: Manifest[List[String]] = scala.collection.immutable.List[java.lang.String]

scala> f(List[Nothing]())
<console>:33: error: No Manifest available for List[T].
              f(List[Nothing]())
               ^

I actually have all the Nothing related bugs (except this one - I assume this one too, but I haven't checked) fixed in a branch, but I'm still experimenting with variations of the approach.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-5505?orig=1
Reporter: @paulp
See #4982