$ git clone -n https://src.fedoraproject.org/rpms/linux-user-chroot.git /var/lib/mock/f45-build-17449-499/root/chroot_tmpdir/scmroot/linux-user-chroot
Cloning into '/var/lib/mock/f45-build-17449-499/root/chroot_tmpdir/scmroot/linux-user-chroot'...
$ git fetch origin a76860e5a0047bd6aa69b972fb4db1ec2da96be2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/linux-user-chroot
 * [new ref]         a76860e5a0047bd6aa69b972fb4db1ec2da96be2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a76860e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild