$ git clone -n https://src.fedoraproject.org/rpms/vkroots.git /var/lib/mock/f45-build-38110-720/root/chroot_tmpdir/scmroot/vkroots
Cloning into '/var/lib/mock/f45-build-38110-720/root/chroot_tmpdir/scmroot/vkroots'...
$ git fetch origin 0e01a716ec7556e957f86ce05bbf8176a5bbb7c5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/vkroots
 * [new ref]         0e01a716ec7556e957f86ce05bbf8176a5bbb7c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0e01a71 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild