The interview started off okay, but this guy joined the call acting hostile right off the bat. He asked me if I knew about 12 factor principles and got defensive when I said they were a marketing campaign launched by Heroku to sell their services. I even remembered a few and listed them off, but he repeated them back to me as if I had gotten them wrong (I hadn't). They still use mainframes. They also just moved from waterfall to agile and had an agile coach on the call.