Use "package:" imports for pub.

test/package_list_files_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.
 
 library packages_list_files_test;
 
 import 'package:path/path.dart' as path;
+import 'package:pub/src/entrypoint.dart';
+import 'package:pub/src/io.dart';
+import 'package:pub/src/system_cache.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
-import '../lib/src/entrypoint.dart';
-import '../lib/src/io.dart';
-import '../lib/src/system_cache.dart';
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
 String root;
 Entrypoint entrypoint;
 
 main() {
   initConfig();
 
   group('not in a git repo', () {
@@ skipping 201 matching lines @@
             unorderedEquals([
           path.join(root, 'packages', 'subfile1.txt'),
           path.join(root, 'packages', 'subfile2.txt'),
           path.join(root, 'packages', 'subsubdir', 'subsubfile1.txt'),
           path.join(root, 'packages', 'subsubdir', 'subsubfile2.txt')
         ]));
       });
     });
   });
 }