Banner patterns created using legacy nbt structures have the color ids inverted

The Bug

Banners created using legacy nbt have their color ids inverted, meaning that white is assigned to 15, orange is 14, black is 0, and so on. Here are some banners created using an online generator. 

Illager Banner: http://www.needcoolshoes.com/banner?=pagvhfilhcawhqht

US Flag: https://www.needcoolshoes.com/banner?=pabBeD

Compare these with the banners I got in the screenshots. The illager banner screenshot has an actual illager banner from killing the petrol leader as a comparison.