$ git clone -n https://src.fedoraproject.org/rpms/gc.git /var/lib/mock/f45-build-9633-407/root/chroot_tmpdir/scmroot/gc
Cloning into '/var/lib/mock/f45-build-9633-407/root/chroot_tmpdir/scmroot/gc'...
$ git fetch origin 54ea1307db744afe894ed9c5a17549ebe181a88f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gc
 * [new ref]         54ea1307db744afe894ed9c5a17549ebe181a88f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 54ea130 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild