def cleanup_old_runroots():

      """

      Those chroots can be lost there for example when the host reboots in the

      middle of runroot generation or in case Pungi task gets killed for

      mounts = [conf.target_dir] + conf.runroot_extra_mounts

      mock_root = "/var/lib/mock"

      for runroot_key in os.listdir(mock_root):

          try:

                  continue

          except OSError:

              continue

  def runroot_tmp_path(runroot_key):

          def mocked_stat(path):

              stat_result = MagicMock()

                  # The "foo/root" is 1 day old, so should be removed.

                  stat_result.st_mtime = time.time() - 24 * 3600

                  # The "already-removed/root" is already removed, so raise an

                  # exception.

                  raise OSError("No such file")

                  # The "bar/root" is just 10 seconds old, so should not be

                  # removed.

                  stat_result.st_mtime = time.time() - 10

          cleanup_old_runroots()