Work around issue 6984.

utils/pub/oauth2.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library oauth2;
 
 import 'dart:io';
 import 'dart:uri';
 
 // TODO(nweiz): Make this a "package:" URL, or something nicer than this.
@@ skipping 139 matching lines @@
   var completer = new Completer();
   var server = new HttpServer();
   server.addRequestHandler((request) => request.path == "/",
       (request, response) {
     chainToCompleter(new Future.immediate(null).chain((_) {
       print('Authorization received, processing...');
       var queryString = request.queryString;
       if (queryString == null) queryString = '';
       response.statusCode = 302;
       response.headers.set('location', 'http://pub.dartlang.org/authorized');
-      response.outputStream.close();
+      return Futures.wait([
+        closeHttpResponse(request, response),
+        grant.handleAuthorizationResponse(queryToMap(queryString))
+      ]);
+    }).transform((results) {
       server.close();
-      return grant.handleAuthorizationResponse(queryToMap(queryString));
+      return results[1];
     }), completer);
   });
   server.listen('127.0.0.1', 0);
 
   var authUrl = grant.getAuthorizationUrl(
       new Uri.fromString('http://localhost:${server.port}'), scopes: _scopes);
 
   print('Pub needs your authorization to upload packages on your behalf.\n'
         'In a web browser, go to $authUrl\n'
         'Then click "Allow access".\n\n'
         'Waiting for your authorization...');
 
   return completer.future.transform((client) {
     print('Successfully authorized.\n');
     return client;
   });
 }