Empty villager trade offer issue

When you create a villager using /summon command which has an empty trade offer the world won't be saved correctly. I can reproduce that bug by creating new world, placing a command block, typing that command:
/summon Villager ~ ~ ~ {PersistenceRequired:1,Offers:{Recipes:[{}]}}, placing a button on that command block and clicking it, then exiting the world and loading it once again. I then had no villager, no button and the command block didn't contain my command. When I make no trade offers, so instead "Recipes:[{}]" I type "Recipes:[]" everything seems to be fine.