$ git clone -n https://src.fedoraproject.org/rpms/HepMC3.git /var/lib/mock/f41-build-815154-149422/root/chroot_tmpdir/scmroot/HepMC3
Cloning into '/var/lib/mock/f41-build-815154-149422/root/chroot_tmpdir/scmroot/HepMC3'...
$ git fetch origin 374e8a5e1e20c738040f80e4d9a6fa80afe36205:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/HepMC3
 * [new ref]         374e8a5e1e20c738040f80e4d9a6fa80afe36205 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 374e8a5 Avoid assert due to implicit narrowing cast on 32 bit architectures