A few issues here:
* This codepath seems artificially mashed into `download_latest_translations` - There's really zero code in common; you added an extra parameter, and force some copying that need not occur.
* The registration po file is for the central server only, so we actually don't need it.
* There are tons of other po files to eliminate / include in this way:
```
python-packages/django/conf/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/admin/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/admin/locale/vi/LC_MESSAGES/djangojs.po
python-packages/django/contrib/admindocs/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/auth/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/comments/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/contenttypes/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/flatpages/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/formtools/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/gis/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/humanize/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/localflavor/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/messages/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/redirects/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/sessions/locale/vi/LC_MESSAGES/django.po
python-packages/django/contrib/sites/locale/vi/LC_MESSAGES/django.po
```