between invocations.
PUXLEJTZQTDKE7YNGJJ2VV2T5OYDRYHGZAYV7OQ6DSMAWI5IF67QC
UZENK33PYWZIWNJMLE2IIXKA6KOCGKGOWUMVBNXAYBOKT2H6ZT6AC
LVJKRTIK5WOWWAZ454B4DCCGETOIQJK5TLOWMZVNY2B4AEGF2GMAC
$tar->add_data("channel/default.nix", $res);
$tar->add_data("channel/default.nix", $res, {mtime => 0});