Saboteurs keep hitting wall even after the target is destroyed

[MAKZIMUS]

Consider this scenario:

1. saboteurs make a mortar inside a solid wall
2. so they try to breach the wall by damaging a wall piece
3. other troops now destroy the mortar
4. but the saboteurs will still keep hitting the wall until the piece is broken, although the target mortar is long gone

This is annoying and puts the lives of the saboteurs in jeopardy. I suggest changing this behavior.