$ git clone -n https://src.fedoraproject.org/rpms/embree.git /var/lib/mock/f39-build-1670686-40851/root/chroot_tmpdir/scmroot/embree
Cloning into '/var/lib/mock/f39-build-1670686-40851/root/chroot_tmpdir/scmroot/embree'...
$ git fetch origin 28f9cde95e8a9cb2d09586f24eff9df6ab8eba28:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/embree
 * [new ref]         28f9cde95e8a9cb2d09586f24eff9df6ab8eba28 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 28f9cde Upload missing source