$ git clone -n https://src.fedoraproject.org/rpms/rust-cast.git /var/lib/mock/f40-build-2061370-49167/root/chroot_tmpdir/scmroot/rust-cast
Cloning into '/var/lib/mock/f40-build-2061370-49167/root/chroot_tmpdir/scmroot/rust-cast'...
$ git fetch origin b799ecced566ad780ff9fcec0baaac596702bf6b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cast
 * [new ref]         b799ecced566ad780ff9fcec0baaac596702bf6b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b799ecc Regenerate with rust2rpm v25