message: Fixes suggested by martinthomson
  Why wait, these are trivial, let's get this PR in.
diff: @@ -10,6 +10,7 @@ use crate::{Error, Header, Res};
  use neqo_common::{matches, qdebug, qinfo, qtrace};
  use neqo_qpack::decoder::QPackDecoder;
  use neqo_transport::Connection;
  +use std::cmp::min;
  use std::mem;
  /*
  @@ -161,17 +162,21 @@ impl ResponseStream {
  pub fn read_response_headers(&mut self) -> Res<(Vec<Header>, bool)> {
  if let ResponseHeadersState::Ready(ref mut headers) = self.response_headers_state {
  - let mut tmp = Vec::new();
  - if let Some(ref mut hdrs) = headers {
  - mem::swap(&mut tmp, hdrs);
  - }
  + let hdrs = if let Some(ref mut hdrs) = headers {
  + mem::replace(hdrs, Vec::new())
  + } else {
  + Vec::new()
  + };
  +
  self.response_headers_state = ResponseHeadersState::Read;
  - let mut fin = false;
  - if self.state == ResponseStreamState::ClosePending {
  - fin = true;
  +
  + let fin = if self.state == ResponseStreamState::ClosePending {
  self.state = ResponseStreamState::Closed;
  - }
  - Ok((tmp, fin))
  + true
  + } else {
  + false
  + };
  + Ok((hdrs, fin))
  } else {
  Err(Error::Unavailable)
  }
  @@ -186,11 +191,7 @@ impl ResponseStream {
  ResponseStreamState::ReadingData {
  ref mut remaining_data_len,
  } => {
  - let to_read = if *remaining_data_len > buf.len() {
  - buf.len()
  - } else {
  - *remaining_data_len
  - };
  + let to_read = min(*remaining_data_len, buf.len());
  let (amount, fin) = conn.stream_recv(self.stream_id, &mut buf[..to_read])?;
  debug_assert!(amount <= to_read);
  *remaining_data_len -= amount;
  