docs: def uninstall_packages():
      """
      Uninstall unwanted packages
      """
      p = server_state('packages_installed')
      if p: installed = set(p)
      else: return
      env.uninstalled_packages[env.host] = []
      #first uninstall any that have been taken off the list
      packages = set(get_packages())
      uninstall = installed - packages
      if uninstall and env.verbosity:
          print env.host,'UNINSTALLING HOST PACKAGES'
      for p in uninstall:
          if env.verbosity:
              print ' - uninstalling',p
          uninstall_package(p)
          env.uninstalled_packages[env.host].append(p)
      set_server_state('packages_installed',get_packages())
      return