Cast headers to list whichever iterable it is (list, tuple, other)
@@ -424,7 +424,7 @@ class RequestResponseCycle:
self.waiting_for_100_continue = False
status_code = message["status"]
- headers = self.default_headers + message.get("headers", [])
+ headers = self.default_headers + list(message.get("headers", []))
if self.access_log:
self.logger.info(
