archive tar compatibility

    # Archive::Tar versions >= 1.09 use the following to enable a compatibility
    # hack so that the resulting archive is compatible with older clients.
    # If no file path is 100 chars or longer, we disable the prefix field
    # for maximum compatibility.  If there are any long file paths then we
    # need the prefix field after all.
    $Archive::Tar::DO_NOT_USE_PREFIX =
      (grep { length($_) >= 100 } @$files) ? 0 : 1;