Use "package:" imports for pub.

test/oauth2/with_a_server_rejected_refresh_token_authenticates_again_test.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.
 
 import 'dart:convert';
 
+import 'package:pub/src/io.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
-import '../../lib/src/io.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 main() {
   initConfig();
   // Regression test for issue 8849.
   integration('with a server-rejected refresh token, authenticates again and '
       'saves credentials.json', () {
     d.validPackage.create();
@@ skipping 22 matching lines @@
     server.handle('GET', '/api/packages/versions/new', (request) {
       expect(request.headers,
           containsPair('authorization', 'Bearer new access token'));
 
       return new shelf.Response(200);
     });
 
     pub.kill();
   });
 }