override template debug in Django 1.8+

test.py

        with override_settings(
            TEMPLATES=[
                {
                    'BACKEND': settings.TEMPLATES[0]['BACKEND'],
                    'DIRS': settings.TEMPLATES[0]['DIRS'],
                    'OPTIONS': {
                        'context_processors': settings.TEMPLATES[0]['OPTIONS']['context_processors'],
                        'loaders': settings.TEMPLATES[0]['OPTIONS']['loaders'],
                        'debug': True,
                    },
                },
            ]
        ):

test2.py

        from copy import deepcopy
        
        TEMPLATES_copy = deepcopy(settings.TEMPLATES)
        TEMPLATES_copy[0]['OPTIONS']['debug'] = True
        with override_settings(
            TEMPLATES=TEMPLATES_copy
        ):