$ git clone -n https://src.fedoraproject.org/rpms/HepMC3.git /var/lib/mock/f38-build-723103-99008/root/chroot_tmpdir/scmroot/HepMC3
Cloning into '/var/lib/mock/f38-build-723103-99008/root/chroot_tmpdir/scmroot/HepMC3'...
$ git fetch origin 020e3dde774475692f78a71e02a0ad849d46c21e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/HepMC3
 * [new ref]         020e3dde774475692f78a71e02a0ad849d46c21e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 020e3dd Update to version 3.2.6