code: func (s *FileSet) WithPrefixedGlobalTruncated(prefix string, fn Iterator) {
  	l.Debugf(`%s WithPrefixedGlobalTruncated("%v")`, s.folder, prefix)
  	s.db.withGlobal([]byte(s.folder), []byte(osutil.NormalizedFilename(prefix)), true, nativeFileIterator(fn))
  }
docs: // Except for an item with a path equal to prefix, only children of prefix are iterated.
  // E.g. for prefix "dir", "dir/file" is iterated, but "dir.file" is not.