Add a SafeHttpServer shim to work around issue 9140.

utils/pub/oauth2.dart

Index: utils/pub/oauth2.dart
diff --git a/utils/pub/oauth2.dart b/utils/pub/oauth2.dart
index 6543ecd06528cbf626ccba93d131b090d1e78bc9..55245f3431c8d99c0b4f809168a4a4ad9e777ece 100644
--- a/utils/pub/oauth2.dart
+++ b/utils/pub/oauth2.dart
@@ -15,6 +15,7 @@ import '../../pkg/pathos/lib/path.dart' as path;
 import 'http.dart';
 import 'io.dart';
 import 'log.dart' as log;
+import 'safe_http_server.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 
@@ -171,7 +172,7 @@ Future<Client> _authorize() {
   // Spin up a one-shot HTTP server to receive the authorization code from the
   // Google OAuth2 server via redirect. This server will close itself as soon as
   // the code is received.
-  return HttpServer.bind('127.0.0.1', 0).then((server) {
+  return SafeHttpServer.bind('127.0.0.1', 0).then((server) {
     var authUrl = grant.getAuthorizationUrl(
         Uri.parse('http://localhost:${server.port}'), scopes: _scopes);