$ git clone -n https://src.fedoraproject.org/rpms/rust-byteorder.git /var/lib/mock/f40-build-2129691-50787/root/chroot_tmpdir/scmroot/rust-byteorder
Cloning into '/var/lib/mock/f40-build-2129691-50787/root/chroot_tmpdir/scmroot/rust-byteorder'...
$ git fetch origin 97c9ef3ddd32a3fa84a064a28208abd1af44bf27:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-byteorder
 * [new ref]         97c9ef3ddd32a3fa84a064a28208abd1af44bf27 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 97c9ef3 Update to version 1.5.0; Fixes RHBZ#2242411