Ignoring treaties combat bug

[Q]

Situation: Empire A has non aggression treaties in all systems with empire B, C and D. Empire B and C have too a non aggression treaty in all systems with each other, but are at war with empire D.
Ships of empire A, B and C are together in a warp point sector and everything is fine until a ship of empire D warps in.
What happens?
What should happen: ships of empire B and C attack together ship of empire D, while ship of empire A does nothing and is not attacked either.
What really happens: Every empire shoots at every other empire ignoring completely all treaties!

Quite a severe bug IMO.