emit new signal

scrapy/core/downloader/__init__.py

@@ -129,6 +129,9 @@ class Downloader(object):
             return response
 
         slot.active.add(request)
+        self.signals.send_catch_log(signal=signals.request_reached_downloader,
+                                    request=request,
+                                    spider=spider)
         deferred = defer.Deferred().addBoth(_deactivate)
         slot.queue.append((request, deferred))
         self._process_queue(spider, slot)