The first import in django/core/template/__init__.py wants to obtain DEFAULT_CHARSET and TEMPLATE_DEBUG from the settings file. Being DJANGO_SETTINGS_MODULE not set, an EnvironmentError exception is raised. If you handle this exception with try/except, defining yourself default values for DEFAULT_CHARSET and TEMPLATE_DEBUG, you have found a (rude) way to change the intended behaviour.
Of course, as already said, this is not an acceptable solution, because: 1) in this way the default charset and template debug settings are hardcoded; 2) still worst, you can't extend the template language with your tags and filters, as their definitions live in a package at the same level as models, views, etc., and so it is coupled to an application. Perhaps, a valid solution would require changes at a deeper level! Thanks for your attention.