Handling locales split into 3 isn't something I've modified (I just added tests to make sure that was still unaffected). The issue that's being addressed here is just that I've been informed that sr_LATN is incorrect it should be sr_Latn. Note whilst looking at this I noticed Django also had a similar problem: see https://code.djangoproject.com/ticket/12230

The bit that need careful handling is if any existing projects are using this so maybe this needs to be backwards compatible for lookup? What do you think?