def existing_files
      files = Set.new
      regex = keep_file_regex
      dirs = keep_dirs

      Utils.safe_glob(site.in_dest_dir, ["**", "*"], File::FNM_DOTMATCH).each do |file|
        next if file =~ HIDDEN_FILE_REGEX || file =~ regex || dirs.include?(file)

        files << file
      end

      files
    end
def existing_files
      files = Set.new
      regex = keep_file_regex
      dirs = keep_dirs

      Utils.safe_glob(site.in_dest_dir, ["**", "*"], File::FNM_DOTMATCH).each do |file|
        next if file =~ HIDDEN_FILE_REGEX || file =~ regex || dirs.include?(file)

        files << file
      end

      files
    end
Private: The list of existing files, apart from those included in
 keep_files and hidden files.

 Returns a Set with the file paths