$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_test.git /var/lib/mock/f39-build-1494683-34542/root/chroot_tmpdir/scmroot/rust-serde_test
Cloning into '/var/lib/mock/f39-build-1494683-34542/root/chroot_tmpdir/scmroot/rust-serde_test'...
$ git fetch origin 6481be443483b8ac3427d80024baacf6a978da76:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_test
 * [new ref]         6481be443483b8ac3427d80024baacf6a978da76 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6481be4 Rebuild for serde_derive fixes