message: Make an assert a debug_assert
  asserts are dangerous.
diff: @@ -360,7 +360,7 @@ impl CongestionControl {
  self.bytes_in_flight,
  self.congestion_window
  );
  - assert!(self.bytes_in_flight <= self.congestion_window);
  + debug_assert!(self.bytes_in_flight <= self.congestion_window);
  }
  fn in_congestion_recovery(&self, sent_time: Instant) -> bool {
  