anchor.diff:        HttpHeaders.LAST_MODIFIED: formatHttpDate(fileStat.changed)
       };
   
  -    var contentType = mime.lookupMimeType(requestedPath);
  +    var contentType = mime.lookupMimeType(fsPath);
       if (contentType != null) {
         headers[HttpHeaders.CONTENT_TYPE] = contentType;
       }
  
positive.code: 
      var segs = [fileSystemPath]..addAll(request.url.pathSegments);
  
      var requestedPath = p.joinAll(segs);
  
      var fileType = FileSystemEntity.typeSync(requestedPath, followLinks: true);
  
      File file = null;
  
      if (fileType == FileSystemEntityType.FILE) {
        file = new File(requestedPath);
      } else if (fileType == FileSystemEntityType.DIRECTORY) {
        file = _tryDefaultFile(requestedPath, defaultDocument);
      }
  
      if (file == null) {
  
negative.code:       }
      }
  
      if (entityType == FileSystemEntityType.DIRECTORY &&
          !request.url.path.endsWith('/')) {
        // when serving the default document for a directory, if the requested
        // path doesn't end with '/', redirect to the path with a trailing '/'
  