$ git clone -n https://src.fedoraproject.org/rpms/poster.git /var/lib/mock/f45-build-28770-633/root/chroot_tmpdir/scmroot/poster
Cloning into '/var/lib/mock/f45-build-28770-633/root/chroot_tmpdir/scmroot/poster'...
$ git fetch origin f20b5aff4b5825c0cc0b614e7ccd8ff2db94937e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/poster
 * [new ref]         f20b5aff4b5825c0cc0b614e7ccd8ff2db94937e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f20b5af Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild