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Ko not detected if old board position is viewed #307
Expected: The move is declared illegal because of ko.
Note that the problem can also occur with superko rules.
This diagram illustrates the problem:
In the situation depicted by the diagram, the ko detection logic must ignore moves 44 and 45 and instead base its decision on the moves up until move 43. The bug was that the ko detection logic did not do that, it based its decision on all the moves ever played in this game, including moves 44 and 45.
In more technical terms, the ko detection logic was using the