message: use iterator .cloned instead of map in IterU32Digits
diff: @@ -2375,7 +2375,7 @@ impl<'a> IterU32Digits<'a> {
  impl<'a> Iterator for IterU32Digits<'a> {
  type Item = u32;
  fn next(&mut self) -> Option<u32> {
  - self.it.next().map(|&t| t)
  + self.it.next().cloned()
  }
  fn size_hint(&self) -> (usize, Option<usize>) {
  