mozilla/affiliates — comment on commit 9e2b8aa68889c9eb431c02f4dec1a293bf4e268c
File: apps/users/tests/test_views.py line 85
By Osmose:

Important to note that this commit is 4 months old...

...but that's changing because, internally, django returns locales with lower-case letters, or at least does when we use the `django.utils.translation.get_language` function to determine the current locale. So we use the lower-case version in our internal storage of locales (as in this case where we're setting the arguments for the profile edit form).