The `DEST_LANG` variable affects rootfs cache content (locale is generated via
`locale-gen "${DEST_LANG}"` before cache is packaged), but it was not included in the
cache hash calculation.
This meant that changing `DEST_LANG` would not invalidate the existing cache,
potentially resulting in images with incorrect locale.
Include `DEST_LANG` in the `hash_hooks` calculation in `calculate_rootfs_cache_id()`.
Changes
- `lib/functions/rootfs/create-cache.sh`: Add `LANG=${DEST_LANG}` to the hash input
Result
Changing `DEST_LANG` now properly invalidates rootfs cache, ensuring the correct locale
is generated.