$ git clone -n https://src.fedoraproject.org/rpms/Hermes.git /var/lib/mock/f42-build-side-1-3501692-45976/root/chroot_tmpdir/scmroot/Hermes
Cloning into '/var/lib/mock/f42-build-side-1-3501692-45976/root/chroot_tmpdir/scmroot/Hermes'...
$ git fetch origin 8e5880485a47c0eecde8598744ab5d13ff8858d7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Hermes
 * [new ref]         8e5880485a47c0eecde8598744ab5d13ff8858d7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8e58804 Fix FTBFS (rhbz#2339848)