Build a list of Origin to load 'template_name' splitted with ':'.
        The first item is the name of the application and the last item
        is the true value of 'template_name' provided by the specified
        application.

def get_template_sources(self, template_name):
        """
        Build a list of Origin to load 'template_name' splitted with ':'.
        The first item is the name of the application and the last item
        is the true value of 'template_name' provided by the specified
        application.
        """
        if ':' not in template_name:
            self.reset(True)
            return

        app, template_path = template_name.split(':')
        if app:
            yield NamespaceOrigin(
                app_name=app,
                name='app_namespace:%s:%s' % (app, template_name),
                template_name=template_path,
                loader=self)
            return

        self.reset(False)
        for app in self.app_templates_dirs:
            file_path = self.get_app_template_path(app, template_path)
            if file_path in self._already_used:
                continue
            self._already_used.append(file_path)
            yield NamespaceOrigin(
                app_name=app,
                name='app_namespace:%s:%s' % (app, template_name),
                template_name=template_path,
                loader=self)