message: Unimplement Hash for SmallSet
  Summary: If someone needs hash, they probably want to use `OrderedSet` (D40443061).
diff: @@ -61,12 +61,6 @@ where
  }
  }
  -impl<T: Hash> Hash for SmallSet<T> {
  - fn hash<H: Hasher>(&self, state: &mut H) {
  - self.0.hash(state)
  - }
  -}
  -
  impl<T> Ord for SmallSet<T>
  where
  T: Ord,
  