$ git clone -n https://src.fedoraproject.org/rpms/esmtp.git /var/lib/mock/f42-build-867434-175505/root/chroot_tmpdir/scmroot/esmtp
Cloning into '/var/lib/mock/f42-build-867434-175505/root/chroot_tmpdir/scmroot/esmtp'...
$ git fetch origin dffc4512034e61d5463f4872fad310338794b24a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/esmtp
 * [new ref]         dffc4512034e61d5463f4872fad310338794b24a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dffc451 Rebuilt for the bin-sbin merge (2nd attempt)