After years this still hasn't been resolved and it's just sad.  I also tried this and still no luck. 

wget <a href="http://repo.ajenti.org/debian/key" class="redactor-autoparser-object">http://repo.ajenti.org/debian/key</a> -O- | sudo apt-key add -

echo "deb [trusted=yes] http://repo.ajenti.org/ng/debian main main ubuntu" | sudo tee /etc/apt/sources.list.d/ajenti.list

sudo apt update

sudo apt -y install ajenti-v ajenti-v-nginx ajenti-v-mysql ajenti-v-php7.2-fpm php7.2-mysql

sudo systemctl restart ajenti