request: Move tornado_handler to ZulipRequestNotes.

zerver/tornado/handlers.py

@@ -111,9 +111,12 @@ class AsyncDjangoHandler(tornado.web.RequestHandler, base.BaseHandler):
         signals.request_started.send(sender=self.__class__)
         request = WSGIRequest(environ)
 
+        # We do the import during runtime to avoid cyclic dependency
+        from zerver.lib.request import get_request_notes
+
         # Provide a way for application code to access this handler
         # given the HttpRequest object.
-        request._tornado_handler = self
+        get_request_notes(request).tornado_handler = self
 
         return request