$ git clone -n https://src.fedoraproject.org/rpms/perl-Package-Pkg.git /var/lib/mock/f45-build-25606-612/root/chroot_tmpdir/scmroot/perl-Package-Pkg
Cloning into '/var/lib/mock/f45-build-25606-612/root/chroot_tmpdir/scmroot/perl-Package-Pkg'...
$ git fetch origin b794660824a7280d8a754a470520eff543305ca6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Package-Pkg
 * [new ref]         b794660824a7280d8a754a470520eff543305ca6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b794660 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild