[Fixed]-Django: iregex is case sensitive

• “LATIN SMALL LETTER C is not considered to be the same as “CYRILLIC SMALL LETTER ES”.
• Ditto for “CYRILLIC SMALL LETTER I” and “CYRILLIC SMALL LETTER SHORT I”
• MySQL’s REGEXP works with bytes not characters. hence only unaccented English letters work in REGEXP; no Cyrillic letter can (reliably) work.
• MariaDB 10.0.5’s REGEXP should do a better job. Ref: https://mariadb.com/kb/en/mariadb/pcre/

I suggest switching to Postgres database which handles non-latin symbols pretty good.

Just tried to reproduce your issue on my Django 1.10 and Postgres 9.6 setup.

from django.contrib.auth.models import User
users = User.objects.filter(username__iregex='Сосницки(и|й)')
users
<QuerySet [<User: Сосницкий>, <User: сосницкий>, <User: сосницкии>, <User: СоСницкии>]>

Seems to be working.