in the moment it can happen that CB1 found metal_above what is right now wanted and so it will forward it first to Output and then it will handover it to CB2. On the whole way to Output of CB2 (Output1-Input2-Height2-Switch2-Slide2 if item have changed-Output2) the item can disappear or change its wanted flag can change to not wanted.
When this happens sorting unit of CB1 does not get updated right now. so that the next item that will become forwarded from CB1 will be an item with hole_above instead again like the one before that was lost: metal_above.
in the moment it can happen that CB1 found metal_above what is right now wanted and so it will forward it first to Output and then it will handover it to CB2. On the whole way to Output of CB2 (Output1-Input2-Height2-Switch2-Slide2 if item have changed-Output2) the item can disappear or change its wanted flag can change to not wanted.
When this happens sorting unit of CB1 does not get updated right now. so that the next item that will become forwarded from CB1 will be an item with hole_above instead again like the one before that was lost: metal_above.
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