delete_empty_directories

# File activesupport/lib/active_support/cache/file_store.rb, line 184
        def delete_empty_directories(dir)
          return if File.realpath(dir) == File.realpath(cache_path)
          if Dir.children(dir).empty?
            Dir.delete(dir) rescue nil
            delete_empty_directories(File.dirname(dir))
          end
        end