$ git clone -n https://src.fedoraproject.org/rpms/rust-jwalk.git /var/lib/mock/f38-build-side-43-rust-devel-1418187-31459/root/chroot_tmpdir/scmroot/rust-jwalk
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1418187-31459/root/chroot_tmpdir/scmroot/rust-jwalk'...
$ git fetch origin 3af9b9ac102db47ed3e8fb0912bc7ec712a409d0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-jwalk
 * [new ref]         3af9b9ac102db47ed3e8fb0912bc7ec712a409d0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3af9b9a Update to version 0.8.1; Fixes RHBZ#2152994