$ git clone -n https://src.fedoraproject.org/rpms/rust-zerocopy /var/lib/mock/f42-build-3432892-45420/root/chroot_tmpdir/scmroot/rust-zerocopy
Cloning into '/var/lib/mock/f42-build-3432892-45420/root/chroot_tmpdir/scmroot/rust-zerocopy'...
$ git fetch origin 5967a1bdc4f2b8041f7e62d900e8d0f6bfbd767c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-zerocopy
 * [new ref]         5967a1bdc4f2b8041f7e62d900e8d0f6bfbd767c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5967a1b Update to version 0.8.21; Fixes RHBZ#2343662