$ git clone -n https://src.fedoraproject.org/rpms/rust-deflate.git /var/lib/mock/f42-build-side-1-3588311-46944/root/chroot_tmpdir/scmroot/rust-deflate
Cloning into '/var/lib/mock/f42-build-side-1-3588311-46944/root/chroot_tmpdir/scmroot/rust-deflate'...
$ git fetch origin eddfb908221c904650d2c84a1bff277d5f0c2c52:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-deflate
 * [new ref]         eddfb908221c904650d2c84a1bff277d5f0c2c52 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eddfb90 no longer needed