The more oil you lose in this unorthodox way without peace treaties, the more you need to farm to get them, the more chance you might be tempted to use crowns to retrain troops before you log out, and the more money they can possibly earn. Unlike the university bug which affects their pocket and was gone in a blink of an eye, or the other bug which uses the "holy light" of castle to block your refinery and was corrected but not this, I have a feeling that this will be here to stay for a long time.