template origin is now public but only set if DEBUG=true; added unit tests for this

see https://github.com/django/django/commit/8625c7aab3760d16572792fea23a95e572e28ead
{% include %} tag accepts variable

if that variable is an object with `render()` it is assumed
to be a template.

see https://github.com/django/django/commit/5cdacbda034af928f5033c9afc7b50ee0b13f75c