In the past this wasn't done before releases; the Git repository
just contained the files from the Translation Project. But this
way it is clearer when comparing release tarballs against the
Git repository. In future releases this might no longer be necessary
within a stable branch as the .po files won't change so easily anymore
when creating a tarball.
Thanks to Marek Černocký.
Other people planning to translate xz: Note that the
messages are a little bit in flux still. Translations
are still welcome, just be prepared to some extra work
in case there are changes.
