def METHOD_NAME(self, request, spider):
    if request.meta.get("dont_merge_cookies", False):
        return
    cookiejarkey = request.meta.get("cookiejar")
    jar = self.jars[cookiejarkey]
    cookies = self._get_request_cookies(jar, request)
    self._process_cookies(cookies, jar=jar, request=request)
    # set Cookie header
    request.headers.pop("Cookie", None)
    jar.add_cookie_header(request)
    self._debug_cookie(request, spider)