Bad state: Stream has already been listened to when accessing response stream in RetryClient.when

[blaugold]

Reading stream of response in when function of RetryClient causes Bad state: Stream has already been listened to to be thrown from https://github.com/dart-lang/http/blob/master/pkgs/http/lib/retry.dart#L125.

Possible fix:

try {
  _unawaited(response.stream.listen((_) {}).cancel().catchError((_) {}));
} catch (_) {}