I’ve become a little wary of operas based on best selling novels and/or Hollywood films so I approached Charles Wuorinen’s Brokeback Mountain with a certain amount of skepticism. I should not have. It’s a Gerard Mortier commission; originally for NYCO but, following that débacle, it followed him to the Teatro Real in Madrid where it premiered in 2014. The libretto is an adaptation by Annie Proulx of her original story. Always a good sign.