$ git clone -n https://src.fedoraproject.org/rpms/rpm.git /var/lib/mock/f45-bootstrap-298-178/root/chroot_tmpdir/scmroot/rpm
Cloning into '/var/lib/mock/f45-bootstrap-298-178/root/chroot_tmpdir/scmroot/rpm'...
$ git fetch origin 7947eaa8915f53a57ba82777b2e168b8c19a66c1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rpm
 * [new ref]         7947eaa8915f53a57ba82777b2e168b8c19a66c1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7947eaa Rebase to 6.1.0 (https://rpm.org/releases/6.1.0)