$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Int64.git /var/lib/mock/f41-build-816051-149980/root/chroot_tmpdir/scmroot/perl-Math-Int64
Cloning into '/var/lib/mock/f41-build-816051-149980/root/chroot_tmpdir/scmroot/perl-Math-Int64'...
$ git fetch origin 13d3a156a7d6b1985bc66e31e646f4a7aaa9343c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Int64
 * [new ref]         13d3a156a7d6b1985bc66e31e646f4a7aaa9343c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 13d3a15 Perl 5.40 rebuild