Fix UNSUBACK messages not being logged.

Closes #903.

Thanks to Christoph Krey.

ChangeLog.txt

@@ -21,6 +21,7 @@ Broker:
 - Fix bridge publishing failing when per_listener_settings was true. Closes
   #860.
 - Fix `use_identity_as_username true` not working. Closes #833.
+- Fix UNSUBACK messages not being logged. Closes #903.
 
 Library:
 - Fix some places where return codes were incorrect, including to the

src/handle_unsubscribe.c

@@ -92,6 +92,8 @@ int handle__unsubscribe(struct mosquitto_db *db, struct mosquitto *context)
 	db->persistence_changes++;
 #endif
 
+	log__printf(NULL, MOSQ_LOG_DEBUG, "Sending UNSUBACK to %s", context->id);
+
 	return send__command_with_mid(context, UNSUBACK, mid, false);
 }