$ git clone -n https://src.fedoraproject.org/rpms/fedora-release.git /var/lib/mock/f42-build-3409018-45145/root/chroot_tmpdir/scmroot/fedora-release
Cloning into '/var/lib/mock/f42-build-3409018-45145/root/chroot_tmpdir/scmroot/fedora-release'...
$ git fetch origin dfc4b870b58ff15a3d87a93504b9c2d77931ef08:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fedora-release
 * [new ref]         dfc4b870b58ff15a3d87a93504b9c2d77931ef08 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dfc4b87 Updates Fedora IoT preset to enable ignition first-boot services