$ git clone -n https://src.fedoraproject.org/rpms/eigen3.git /var/lib/mock/f45-build-8050-374/root/chroot_tmpdir/scmroot/eigen3
Cloning into '/var/lib/mock/f45-build-8050-374/root/chroot_tmpdir/scmroot/eigen3'...
$ git fetch origin 62826042b81705dd4164bd7142e157d993bd261a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/eigen3
 * [new ref]         62826042b81705dd4164bd7142e157d993bd261a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6282604 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild