django/django — pull request #3700 by coldmind (2014-12-06 20:52:58+00:00)
Title: Fixed #23405 - Fixed asking for default value for `CharField` and `TextField` in migrations

I think modifying autodetector will be enough.
When migration will be applying, `django.db.backends.schema.BaseDatabaseSchemaEditor#effective_default` set correct value (empty string) for `TextField` and `CharField`, if they are blank, but NOT NULL.