$ git clone -n https://src.fedoraproject.org/rpms/exiv2.git /var/lib/mock/f40-build-2198051-51687/root/chroot_tmpdir/scmroot/exiv2
Cloning into '/var/lib/mock/f40-build-2198051-51687/root/chroot_tmpdir/scmroot/exiv2'...
$ git fetch origin cc89acdb97b636bc7ddddc4b866432c0a27cd839:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/exiv2
 * [new ref]         cc89acdb97b636bc7ddddc4b866432c0a27cd839 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cc89acd 0.28.0