$ git clone -n https://src.fedoraproject.org/rpms/rust-rayon.git /var/lib/mock/f40-build-2144520-50868/root/chroot_tmpdir/scmroot/rust-rayon
Cloning into '/var/lib/mock/f40-build-2144520-50868/root/chroot_tmpdir/scmroot/rust-rayon'...
$ git fetch origin 20cf22b7b04f6ea3d089d57a94c535c7664db142:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rayon
 * [new ref]         20cf22b7b04f6ea3d089d57a94c535c7664db142 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 20cf22b Update to version 1.8.0; Fixes RHBZ#2239945