$ git clone -n https://src.fedoraproject.org/rpms/exiv2.git /var/lib/mock/f41-build-815455-149526/root/chroot_tmpdir/scmroot/exiv2
Cloning into '/var/lib/mock/f41-build-815455-149526/root/chroot_tmpdir/scmroot/exiv2'...
$ git fetch origin 309138d042947dc911a3c7ea50c2a99952f3a71a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/exiv2
 * [new ref]         309138d042947dc911a3c7ea50c2a99952f3a71a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 309138d Fix sources file