add cache list command to pub

utils/pub/git_source.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 git_source;
 
 import 'dart:async';
 
 import '../../pkg/pathos/lib/path.dart' as path;
 
@@ skipping 98 matching lines @@
 
   /// Attaches a specific commit to [id] to disambiguate it.
   Future<PackageId> resolveId(PackageId id) {
     return _revisionAt(id).then((revision) {
       var description = {'url': _getUrl(id), 'ref': _getRef(id)};
       description['resolved-ref'] = revision;
       return new PackageId(id.name, this, id.version, description);
     });
   }
 
+  // TODO(keertip): Implement getCachedPackages().
+  
   /// Ensure that the canonical clone of the repository referred to by [id] (the
   /// one in `<system cache>/git/cache`) exists and is up-to-date. Returns a
   /// future that completes once this is finished and throws an exception if it
   /// fails.
   Future _ensureRepoCache(PackageId id) {
     return defer(() {
       var path = _repoCachePath(id);
       if (!entryExists(path)) return _clone(_getUrl(id), path, mirror: true);
       return git.run(["fetch"], workingDir: path).then((result) => null);
     });
@@ skipping 71 matching lines @@
     return description['ref'];
   }
 
   /// Returns [description] if it's a description, or [PackageId.description] if
   /// it's a [PackageId].
   _getDescription(description) {
     if (description is PackageId) return description.description;
     return description;
   }
 }