post_upgrade() {
  if (( $(vercmp "$2" '1:0.7.0') < 0 )); then
    cat <<MSG
==> lrzip 0.7.x uses a new file format. Most archives remain readable by
    0.6x, except:
    - large files compressed via stdio (new streaming format)
    - encrypted files (now AES-256-GCM); use --legacy-encrypt to create
      archives that 0.6x can decrypt. This option will be deprecated.
    Archives created by 0.6x can still be decompressed by 0.7x.
MSG
  fi
}
