Denormalizes ``Badge.users.count()`` into ``Bagdes.users_count`` field.

def update_badge_users_count(self):
        """
        Denormalizes ``Badge.users.count()`` into ``Bagdes.users_count`` field.
        """
        logger.debug('→ Badge %s: syncing users count...', self.slug)

        badge, updated = self.badge, False

        if not badge:
            logger.debug(
                '✘ Badge %s: does not exist in the database (run badgify_sync badges)',
                self.slug)
            return (self.slug, updated)

        old_value, new_value = badge.users_count, badge.users.count()

        if old_value != new_value:
            badge = Badge.objects.get(slug=self.slug)
            badge.users_count = new_value
            badge.save()
            updated = True

        if updated:
            logger.debug('✓ Badge %s: updated users count (from %d to %d)',
                         self.slug,
                         old_value,
                         new_value)
        else:
            logger.debug('✓ Badge %s: users count up-to-date (%d)',
                         self.slug,
                         new_value)

        return (badge, updated)