[1938] added a log message in notify_out when receiving a valid response.

mainly for rationalizing lettuce tests that are coming after this.

src/lib/python/isc/notify/notify_out.py

@@ -570,6 +570,10 @@ class NotifyOut:
             logger.error(NOTIFY_OUT_REPLY_UNCAUGHT_EXCEPTION, err)
             return _BAD_REPLY_PACKET
 
+        logger.debug(logger.DBGLVL_TRACE_BASIC, NOTIFY_OUT_REPLY_RECEIVED,
+                     zone_notify_info.zone_name, zone_notify_info.zone_class,
+                     from_addr[0], from_addr[1], msg.get_rcode())
+
         return _REPLY_OK
 
     def _get_notify_reply(self, sock, tgt_addr):

src/lib/python/isc/notify/notify_out_messages.mes

@@ -60,6 +60,11 @@ given address, but the reply did not have the QR bit set to one.
 Since there was a response, no more notifies will be sent to this
 server for this notification event.
 
+% NOTIFY_OUT_REPLY_RECEIVED Zone %1/%2: notify response from %3:%4: %5
+The notify_out library sent a notify message to the nameserver at
+the given address, and received a response.  Its Rcode will be shown,
+too.
+
 % NOTIFY_OUT_REPLY_UNCAUGHT_EXCEPTION uncaught exception: %1
 There was an uncaught exception in the handling of a notify reply
 message, either in the message parser, or while trying to extract data