Please check warning messages.

```ruby
  def rename_taps_dir_if_necessary
    need_repair_taps = false
    Dir["#{HOMEBREW_LIBRARY}/Taps/*/"].each do |tapd|
      tapd_basename = File.basename(tapd)

      if File.directory?(tapd + "/.git")
        if tapd_basename.include?("-")
          # only replace the *last* dash: yes, tap filenames suck
          user, repo = tapd_basename.reverse.sub("-", "/").reverse.split("/")

          FileUtils.mkdir_p("#{HOMEBREW_LIBRARY}/Taps/#{user.downcase}")
          FileUtils.mv(tapd, "#{HOMEBREW_LIBRARY}/Taps/#{user.downcase}/#{repo.downcase}")
          need_repair_taps = true

          if tapd_basename.count("-") >= 2
            opoo "Homebrew changed the structure of Taps like <someuser>/<sometap>.\n"\
              + "So, you may need to rename #{HOMEBREW_LIBRARY}/Taps/#{user.downcase}/#{repo.downcase} manually."
          end
        else
          opoo "#{tapd} is incorrect name format. You may need to rename it like <someuser>/<sometap> manually."
        end
      end
    end

    repair_taps if need_repair_taps
  end
```