Villagers detect pandas being hurt, even when they are separated with a wall

Villagers generate angry particles when a panda is hurt near them (MC-140813). However, this behavior is also exhibited when the panda is behind a wall that the villager is near.

How to reproduce:

1. Spawn a villager
2. Make a wall near the villager
3. Spawn a panda behind the wall
4. Hurt the panda

Sorry for the bad screenshot; i was trying to capture the moment when the villager made particles.