Don't implicitly run "pub get".

lib/src/command/list_package_dirs.dart

 // Copyright (c) 2013, 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 pub.command.list_package_dirs;
 
 import 'package:path/path.dart' as p;
 
 import '../command.dart';
+import '../io.dart';
 import '../log.dart' as log;
 import '../utils.dart';
 
 /// Handles the `list-package-dirs` pub command.
 class ListPackageDirsCommand extends PubCommand {
   String get name => "list-package-dirs";
   String get description => "Print local paths to dependencies.";
   String get invocation => "pub list-package-dirs";
   bool get takesArguments => false;
   bool get hidden => true;
 
   ListPackageDirsCommand() {
     argParser.addOption("format",
         help: "How output should be displayed.",
         allowed: ["json"]);
   }
 
   void run() {
     log.json.enabled = true;
 
-    if (!entrypoint.lockFileExists) {
+    if (!fileExists(entrypoint.lockFilePath)) {
       dataError('Package "myapp" has no lockfile. Please run "pub get" first.');
     }
 
     var output = {};
 
     // Include the local paths to all locked packages.
     var packages = mapMap(entrypoint.lockFile.packages, value: (name, package) {
       var source = entrypoint.cache.sources[package.source];
       var packageDir = source.getDirectory(package);
       // Normalize paths and make them absolute for backwards compatibility
@@ skipping 11 matching lines @@
     // that's just the pubspec and lockfile.
     output["input_files"] = [
       p.normalize(p.absolute(entrypoint.lockFilePath)),
       p.normalize(p.absolute(entrypoint.pubspecPath))
     ];
 
     log.json.message(output);
   }
 }