$ git clone -n https://src.fedoraproject.org/rpms/rust-eif_build.git /var/lib/mock/f40-build-861790-170358/root/chroot_tmpdir/scmroot/rust-eif_build
Cloning into '/var/lib/mock/f40-build-861790-170358/root/chroot_tmpdir/scmroot/rust-eif_build'...
$ git fetch origin cae40e229798b442cc8489d9ef3155d29853e2b9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-eif_build
 * [new ref]         cae40e229798b442cc8489d9ef3155d29853e2b9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cae40e2 Initial package (rhbz#2310837)