Back in '86, I worked at the as an ice cream scooper at Haagan Dazs in the Danbury Fair Mall. Back then, Haagan Dazs didn't have pistachio, and people always asked for it....
I don't know if it was company policy, or just something crazy our local manager told us to say, but the official response we were to give was "sorry, we don't make pistachio and never will, because Haagan Dazs doesn't use green food coloring". Despite uttering this to customers multiple times myself, it always seemed a bit bat-crazy. I mean, didn't anyone think to make pistachio ice cream *without the green food coloring*?
Here in 2017, I was amused to see the pistchio being offered at a local convenient store. Of course I had to buy it, and wasn't the slightest bit surprised to see that it is, in fact, white.