It's a cancelled order from ATLAS that was sitting around on the ramp @ KPAE. I suspect (but have no solid info) it's an attempt by the big 'B' to play 'kiss and make up' with the employees and the region to compensate for the severe case of 'bad taste in the mouth' caused by the 777X follies.
If you are interested, the aircraft IS still for sale.
If you live in the Denver area, be sure and watch for it to fly around the metro Denver skies on Saturday mid morning before it leaves for Noo Joisey-
12TH MAN BABY!!!!!!