anchor.diff:  
     void _writeHeaders() {
       if (_headersWritten) return;
  -    bool _tmpIgnoreBody = _ignoreBody;
  -    _ignoreBody = false;
       _headersWritten = true;
       _writeHeader();
  -    _ignoreBody = _tmpIgnoreBody;
       if (_ignoreBody) {
         _ioSink.close();
         return;
  
positive.code:     headers._finalize();
  
      // Write headers.
      headers._write(this);
      writeCRLF();
    }
  }
  
negative.code:   HttpConnectionInfo get connectionInfo => _httpRequest.connectionInfo;
  
    void _writeHeader() {
      writeSP() => _ioSink.add([_CharCode.SP]);
      writeCRLF() => _ioSink.add([_CharCode.CR, _CharCode.LF]);
  
      // Write status line.
      if (headers.protocolVersion == "1.1") {
        _ioSink.add(_Const.HTTP11);
      } else {
        _ioSink.add(_Const.HTTP10);
      }
      writeSP();
      _ioSink.addString(statusCode.toString());
      writeSP();
      _ioSink.addString(reasonPhrase);
      writeCRLF();
  
      var session = _httpRequest._session;
  