$ git clone -n https://src.fedoraproject.org/rpms/mb2md.git /var/lib/mock/f45-build-18149-510/root/chroot_tmpdir/scmroot/mb2md
Cloning into '/var/lib/mock/f45-build-18149-510/root/chroot_tmpdir/scmroot/mb2md'...
$ git fetch origin 62993afe4bd0eb0ecbd71f0cfd2f11ee2ff5bc2d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mb2md
 * [new ref]         62993afe4bd0eb0ecbd71f0cfd2f11ee2ff5bc2d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62993af Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild