Confusing error text

[anton-kazlouski]

I'm not English native, but the error message seems to have a logical error:
This field may not be null -- means that a field might be null and might not be null (negative probability). But the translation means that the field is required and cannot be null.

django-rest-framework/rest_framework/locale/ru_RU/LC_MESSAGES/django.po

Line 160 in 3578683

msgid "This field may not be null."

I've checked with Django sources and found this:
This field cannot be null which seems to me more accurate.

I want to clarify it's an actual mistake. If yes, I'll create a PR to fix this issue.