Merge branch 'maint'

* maint:
  http.c: set slot callback members to NULL when releasing object

http.c

@@ -1289,5 +1289,10 @@ void release_http_object_request(struct http_object_request *freq)
 		free(freq->url);
 		freq->url = NULL;
 	}
+	if (freq->slot != NULL) {
+		freq->slot->callback_func = NULL;
+		freq->slot->callback_data = NULL;
+		release_active_slot(freq->slot);
 		freq->slot = NULL;
 	}
+}