By default, vlilagers will ignore “peaceful” fauna like deer, sheep and un-aggroed boars when given an attack move command. They will attack wolves when given an attack move command. This behavior makes sense.
However, once a boar is directly attacked (by either player) and begins attacking nearby units, I would expect that villagers given at attack-move command would now acquire the boar as a target. Instead, they continue to ignore the boar, unless explicitly given a command to attack the boar directly.
1.) Bring a group of villagers near a peaceful boar.
2.) Attack the boar directly with a single villager.
3.) Give the rest of the villagers and attack-move command towards the boar.
The villagers run past the boar.
The villagers attack the boar.