anchor.diff:        } else {
           status.type = oldStatus.type;
         }
  -    } else {
  -      status.headSha = status.sha;
  -      status.type = FileStatusType.UNTRACKED;
       }
       _statusIdx[status.path] = status;
       _scheduleWriteIndex();
  
positive.code:             }
              break;
            case FileStatusType.UNTRACKED:
              status.type = FileStatusType.UNTRACKED;
              break;
            default:
              throw "Unsupported file status type.";
  
negative.code:              return new Future.value();
             });
           } else {
             // don't update index for untracked files.
             if (_statusIdx[entry.fullPath] != null) {
               return getShaForEntry(entry, 'blob').then((String sha) {
                 return entry.getMetadata().then((data) {
                   FileStatus status = new FileStatus();
                   status.path = entry.fullPath;
                   status.sha = sha;
                   status.size = data.size;
                   updateIndexForEntry(status);
                   filePaths.add(entry.fullPath);
                 });
               });
             }
           }
        }).then((_) {
          _updateDeletedFiles(filePaths);
  