$ git clone -n https://src.fedoraproject.org/rpms/rust-ref-cast.git /var/lib/mock/f40-build-2260568-54413/root/chroot_tmpdir/scmroot/rust-ref-cast
Cloning into '/var/lib/mock/f40-build-2260568-54413/root/chroot_tmpdir/scmroot/rust-ref-cast'...
$ git fetch origin 9d63738680c19e2693694366037c8cf8cd974c2e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-ref-cast
 * [new ref]         9d63738680c19e2693694366037c8cf8cd974c2e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9d63738 Update to version 1.0.22; Fixes RHBZ#2254419