$ git clone -n https://src.fedoraproject.org/rpms/gram_grep.git /var/lib/mock/f45-build-12976-444/root/chroot_tmpdir/scmroot/gram_grep
Cloning into '/var/lib/mock/f45-build-12976-444/root/chroot_tmpdir/scmroot/gram_grep'...
$ git fetch origin 4ef62a64f6fcd692eb5236f1ed2fbde8c10ece2e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gram_grep
 * [new ref]         4ef62a64f6fcd692eb5236f1ed2fbde8c10ece2e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4ef62a6 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild