only log message if response is appended

Closes: #685

Author: matthiasschaub

vcr/cassette.py

@@ -225,10 +225,10 @@ def write_protected(self):
 
     def append(self, request, response):
         """Add a request, response pair to this cassette"""
-        log.info("Appending request %s and response %s", request, response)
         request = self._before_record_request(request)
         if not request:
             return
+        log.info("Appending request %s and response %s", request, response)
         # Deepcopy is here because mutation of `response` will corrupt the
         # real response.
         response = copy.deepcopy(response)