$ git clone -n https://src.fedoraproject.org/rpms/exim.git /var/lib/mock/f42-build-867436-175505/root/chroot_tmpdir/scmroot/exim
Cloning into '/var/lib/mock/f42-build-867436-175505/root/chroot_tmpdir/scmroot/exim'...
$ git fetch origin 035a0908a258cfece63ef5f196ff76cf08519b29:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/exim
 * [new ref]         035a0908a258cfece63ef5f196ff76cf08519b29 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 035a090 Rebuilt for the bin-sbin merge (2nd attempt)