Comment 2 for bug 1914084

Seems that this is due to Idf4269a2ae5ce9863e1eda2f824e7a9fc93847d2 (Generate inventory without any overcloud). In fact passing "--stack overcloud" to it fixes it for me. I think if nothing else we should print a proper error message and/or restore the previous default behaviour of this working without having to specify the stack?