anchor.diff:  class FileStatus {
     String path;
     String headSha;
  +  String permission;
     String sha;
     int size;
     bool deleted = false;
  
positive.code:       'sha' : sha,
        'size' : size,
        'modificationTime' : modificationTime,
        'type' : type,
        'deleted' : deleted
      };
  
negative.code:       status.headSha = statusMap['headSha'];
        status.sha = statusMap['sha'];
        status.modificationTime = statusMap['modificationTime'];
        status.permission = statusMap['permission'];
        status.path = statusMap['path'];
        status.size = statusMap['size'];
        status.type = statusMap['type'];
  