Cannot modify speakers in ACP when slug is not alphanumeric ASCII

[wfdd]

Steps to reproduce:

1. Create a new speaker whose name includes non-ASCII characters via /speaker/add; or import speakers from Popolo JSON
2. In the ACP, under 'Speakers', click on the speaker to modify
3. Press 'Save'

Django warns, "Enter a valid 'slug' consisting of letters, numbers, underscores or hyphens".

[wfdd]

On further inspection, this probably needs to be fixed in mysociety/django-sluggable; mozilla/unicode-slugify#10 may be of relevance.

[dracos]

Thanks; I see that Django 1.9 added an allow_unicode argument to SlugField which would fix this: https://docs.djangoproject.com/en/1.9/releases/1.9/ – we'll implement something like the issue you link to, to continue supporting 1.8.