anchor.diff:     * Returns a map from the file path to the file status.
      */
     static Future<Map<String, FileStatus>> getFileStatuses(ObjectStore store) {
  -    return store.index.updateIndex().then((_) {
  +    return store.index.updateIndex(true).then((_) {
         return store.index.statusMap;
       });
     }
  
positive.code:    * usage in the future.
     */
    static Future isWorkingTreeClean(ObjectStore store) {
      return _getFileStatusesForTypes(store, [FileStatusType.MODIFIED,
          FileStatusType.STAGED]).then((r) {
        if (!r.isEmpty) {
          //TODO(grv) : throw custom exception.
          throw "Uncommitted changes in the working tree.";
        }
      });
    }
  
    static Future<Map<String, FileStatus>> getUnstagedChanges(ObjectStore store)
        => _getFileStatusesForTypes(store, [FileStatusType.MODIFIED]);
  
    static Future<Map<String, FileStatus>> getStagedChanges(ObjectStore store)
        => _getFileStatusesForTypes(store, [FileStatusType.STAGED]);
  
    static Future<Map<String, FileStatus>> getUntrackedChanges(ObjectStore store)
        => _getFileStatusesForTypes(store, [FileStatusType.UNTRACKED]);
  
    static Future<List<String>> getDeletedFiles(ObjectStore store) {
      return _getFileStatusesForTypes(store, [FileStatusType.MODIFIED], false)
          .then(
          (Map<String, FileStatus> statuses) {
        List<String> deletedFilesStatus = [];
        statuses.forEach((String filePath, FileStatus status) {
          if (status.deleted) {
            deletedFilesStatus.add(filePath);
          }
        });
        return deletedFilesStatus;
      });
    }
  
    static Future<Map<String, FileStatus>> _getFileStatusesForTypes(
        ObjectStore store, List<String> types, [bool updateSha=true]) {
      return store.index.updateIndex(updateSha).then((_) {
        Map result = {};
        store.index.statusMap.forEach((k, v) {
          if (types.any((type) => v.type == type)) {
            result[k] = v;
          }
        });
        return result;
      });
    }
  }
  
negative.code:         return status;
        }
  
        if (entry.isDirectory) {
          return status;
        }
  
        // TODO(grv) : check the modification time when it is available.
        return getShaForEntry(entry, 'blob').then((String sha) {
          status = new FileStatus();
  