desc 'wipe', 'Uninstall all RubyGems related to Merb'
    def wipe
      windows = PLATFORM =~ /win32|cygwin/ rescue nil
      sudo = windows ? "" : "sudo"
      `gem list merb`.split("\n").each do |line|
        next unless line =~ /^(merb[^ ]+)/
        system("#{sudo} gem uninstall #{$1} -a -I -x; true")
      end
      system("#{sudo} gem uninstall extlib -a -I -x")
    end