message: fix `Parents` iterator skipping immediate parent
diff: @@ -303,8 +303,9 @@ where
  impl<'a> Iterator for Parents<'a> {
  type Item = &'a SpanData;
  fn next(&mut self) -> Option<Self::Item> {
  + let next = self.next;
  self.next = self.next.and_then(SpanData::parent);
  - self.next
  + next
  }
  }
  