TC auto shooting boar with weak vill?

I've always liked the idea of using the TC to weaken the boar before killing it with a vill but lately I've been struggling with a specific scenario that means the TC ends up killing the boar.

I garrison the vills on sheep in the TC and shoot the boar once or twice and then ungarrison them. The weak vill that has taken a few hits from the boar then shoots the boar dead when they go in the TC to escape from being killed. The TC seems to remember that it was shooting at the boar so that as soon as I garrison, boom, the boar is dead. How do you get around this? Do you just have to not garrison your weak vill until the boar is dead?