Villagers will change their professions even when you trade with them first

I had a villager with a very good diamond sword trade who was all maxed out. I broke the villager's work block to try and move him into a prison cell(uh... i mean trading hall). Then, he turned into a maxed out leatherworker!!! I think the only cauldron in my world is thousands of blocks away, inside a village I explored a long time ago!!! I want my god tier diamond sword villager back!!!