anchor.diff:  
       _logResponse(streamedResponse);
   
  -    var status = streamedResponse.statusCode;
  -    // 401 responses should be handled by the OAuth2 client. It's very
  -    // unlikely that they'll be returned by non-OAuth2 requests. We also want
  -    // to pass along 400 responses from the token endpoint.
  -    var tokenRequest = streamedResponse.request.url == oauth2.tokenEndpoint;
  -    if (status < 400 || status == 401 || (status == 400 && tokenRequest)) {
  -      return streamedResponse;
  -    }
  -
  -    if (status == 406 &&
  -        request.headers['Accept'] == PUB_API_HEADERS['Accept']) {
  -      fail("Pub ${sdk.version} is incompatible with the current version of "
  -          "${request.url.host}.\n"
  -          "Upgrade pub to the latest version and try again.");
  -    }
  -
  -    if (status == 500 &&
  -        (request.url.host == "pub.dartlang.org" ||
  -            request.url.host == "storage.googleapis.com")) {
  -      var message = "HTTP error 500: Internal Server Error at "
  -          "${request.url}.";
  -
  -      if (request.url.host == "pub.dartlang.org" ||
  -          request.url.host == "storage.googleapis.com") {
  -        message += "\nThis is likely a transient error. Please try again "
  -            "later.";
  -      }
  -
  -      fail(message);
  -    }
  -
  -    throw new PubHttpException(
  -        await http.Response.fromStream(streamedResponse));
  +    return streamedResponse;
     }
   
     /// Whether extra metadata headers should be added to [request].
  
positive.code: /// we're waiting for them to come back up.
  final _retriedHosts = new Set<String>();
  
  /// The HTTP client to use for all HTTP requests.
  final httpClient = new ThrottleClient(
      16,
      new RetryClient(_pubClient,
          retries: 5,
          when: (response) => const [502, 503, 504].contains(response.statusCode),
          delay: (retryCount) {
  
negative.code:           log.message(
                "It looks like ${request.url.host} is having some trouble.\n"
                "Pub will wait for a while before trying to connect again.");
          })));
  
  /// The underlying HTTP client wrapped by [httpClient].
  http.Client get innerHttpClient => _pubClient._inner;
  