message: test(http1): only enable WriteBuf non-empty test with debug-assertions
  Closes
diff: @@ -790,6 +790,7 @@ mod tests {
  #[test]
  #[should_panic]
  + #[cfg(debug_assertions)] // needs to trigger a debug_assert
  fn write_buf_requires_non_empty_bufs() {
  let mock = Mock::new().build();
  let mut buffered = Buffered::<_, Cursor<Vec<u8>>>::new(mock);
  