Properly app_template_dirs when INSTALLED_APPS change.

from django.utils._os import safe_join

from django.utils import six

# At compile time, cache the directories to search.

def calculate_app_template_dirs():

    if six.PY2:

        fs_encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()

    app_template_dirs = []

            if six.PY2:

                template_dir = template_dir.decode(fs_encoding)

            app_template_dirs.append(template_dir)

    return tuple(app_template_dirs)

# It won't change, so convert it to a tuple to save memory.

app_template_dirs = tuple(app_template_dirs)

# At compile time, cache the directories to search.

app_template_dirs = calculate_app_template_dirs()

class Loader(BaseLoader):

        # Rebuild any AppDirectoriesFinder instance.

        from django.contrib.staticfiles.finders import get_finder

        get_finder.cache_clear()

        # Rebuild app_template_dirs cache.

        from django.template.loaders import app_directories as mod

        mod.app_template_dirs = mod.calculate_app_template_dirs()

@receiver(setting_changed)