$ git clone -n https://src.fedoraproject.org/rpms/postproof.git /var/lib/mock/f45-build-28851-633/root/chroot_tmpdir/scmroot/postproof
Cloning into '/var/lib/mock/f45-build-28851-633/root/chroot_tmpdir/scmroot/postproof'...
$ git fetch origin 4ba567f2d5e7fc980378daaa904f5ca5ce7dbb73:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/postproof
 * [new ref]         4ba567f2d5e7fc980378daaa904f5ca5ce7dbb73 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4ba567f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild