I have an automatic wheat farm with a villager with an inventory full of seeds. It worked perfectly when I made it in 1.9, and it worked as well in 1.10. But now I upgraded to 1.10.1 and 1.10.2 and the villager stopped farming wheat. The potato and carrot farmers are still farming, but the farmer meant to farm wheat just stands there idle. He is looking at fully grown carrots/potatos in the other farms, but he's not farming fully grown wheat, nor is he replanting on empty farmland. I respawned in new farmer villagers via both commands and spawn eggs, but if they are spawned in 1.10.1 or 1.10.2 they don't farm either. When I revert back to 1.10, the villagers spawned in 1.10.1 or 1.10.2 still don't farm. However, if I spawn a new villager in 1.10, it does start farming. So something in 1.10.1 and 1.10.2 is stopping farmers from farming wheat, and it affects the villagers as they don't farm anymore when you revert back to 1.10 either.
So in conclusion, only villagers spawned in version 1.10 or older will farm wheat in version 1.10 or older.