void CFactory::KillUnit(CUnit* attacker, bool selfDestruct, bool reclaimed, int weaponDefID)
{
	RECOIL_DETAILED_TRACY_ZONE;
	if (curBuild != nullptr) {
		curBuild->KillUnit(nullptr, false, true, -CSolidObject::DAMAGE_FACTORY_KILLED);
		curBuild = nullptr;
	}

	CUnit::KillUnit(attacker, selfDestruct, reclaimed, weaponDefID);
}

This patch of code supposedly is responsible for killing buildee from a lab upon death.
But when the death is caused by Spring.DestroyUnit, unit->ForcedKillUnit() is called and this isn't, meaning a buildee will stay alive.
unit->ForcedKillUnit(attacker, selfDestr, reclaimed, -CSolidObject::DAMAGE_KILLED_LUA);
Maybe add an exception for factories that would have to call both unit->ForcedKillUnit() and factory->curBuild -> KillUnit ?