$ git clone -n https://src.fedoraproject.org/rpms/rust-nu-std.git /var/lib/mock/f40-build-2613550-64071/root/chroot_tmpdir/scmroot/rust-nu-std
Cloning into '/var/lib/mock/f40-build-2613550-64071/root/chroot_tmpdir/scmroot/rust-nu-std'...
$ git fetch origin 73de1b1e31ded2fd0bc72f0827637d1cf856955c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nu-std
 * [new ref]         73de1b1e31ded2fd0bc72f0827637d1cf856955c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 73de1b1 Update to 0.91.0 (rhbz#2257512)