$ git clone -n https://src.fedoraproject.org/rpms/perl-prefork.git /var/lib/mock/f45-build-27735-625/root/chroot_tmpdir/scmroot/perl-prefork
Cloning into '/var/lib/mock/f45-build-27735-625/root/chroot_tmpdir/scmroot/perl-prefork'...
$ git fetch origin 940af98a64b47d4738a7698f1a9f7d9bbf928e10:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-prefork
 * [new ref]         940af98a64b47d4738a7698f1a9f7d9bbf928e10 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 940af98 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild