$ git clone -n https://src.fedoraproject.org/rpms/rust-pretty-bytes.git /var/lib/mock/f38-build-side-42-init-devel-1394848-31050/root/chroot_tmpdir/scmroot/rust-pretty-bytes
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1394848-31050/root/chroot_tmpdir/scmroot/rust-pretty-bytes'...
$ git fetch origin b3cc5b6ad025643f21416cd89994d963d27945c5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-pretty-bytes
 * [new ref]         b3cc5b6ad025643f21416cd89994d963d27945c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b3cc5b6 Drop binary which is only useful for upstream development