When I encountered some zombie villagers in my desert after I had updated to 1.11, they seemed to have the clothes of Plains villagers. I noticed that the ones that I had captured before the update had their desert clothes. I have encountered these Plains zombies from both a zombie monster spawner in my desert and from the ones that randomly spawn in the overworld at night. I have not seen any Desert-clothed villagers except for the ones that existed from before the update.