$ git clone -n https://src.fedoraproject.org/rpms/perl-Test-Vars.git /var/lib/mock/f40-build-2630084-65626/root/chroot_tmpdir/scmroot/perl-Test-Vars
Cloning into '/var/lib/mock/f40-build-2630084-65626/root/chroot_tmpdir/scmroot/perl-Test-Vars'...
$ git fetch origin 7681f8d8e3ee501f7cf771d35bf2003a4b3003de:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Test-Vars
 * [new ref]         7681f8d8e3ee501f7cf771d35bf2003a4b3003de -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7681f8d FTBFS with Perl 5.38, no activity upstream (rhbz#2223392)