def isConnectionControlHeader(self, name):
        """
        Content-Length in the response to a HEAD request is an entity header,
        not a connection control header.
        """
        if self.request.method == b'HEAD' and name == b'content-length':
            return False
        return HTTPParser.isConnectionControlHeader(self, name)

        Content-Length in the response to a HEAD request is an entity header,
        not a connection control header.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/_newclient.py