When creating a line of command blocks that pass a redstone block forward every tick, it activates touching repeat blocks twice.
Here's the arrangement for the first screenshot:
Normal command block: clone ~ ~ ~-1 ~ ~ ~-1 ~1 ~ ~-1 replace move
Repeating command block: say 1
Here's the arrangement for the second and third screenshot:
Repeating command block: say 1
Chain command block: clone ~ ~ ~2 ~ ~ ~2 ~1 ~ ~2 replace move
The bug occurs in both cases. If required, I can shoot video footage.
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Comments 4
Might be MC-92629
This is still the case, as demonstrated in the video I just uploaded.
A workaround is to switch the triggered command block's type to impulse, and chain blocks react to them just as well, and it's only ran once.
This is due to block update order from the redstone block (and is the purpose of the introduction of Chain command blocks), and determines which command block is queued first.
If the Repeating is queued first (as it is in the example video), it gets to re-queue itself because the redstone block is still powering it at the time of execution, and then the Impulse block moves the redstone block. If the Impulse is queued first, the redstone block is moved before the Repeating block executes and checks for a power source to re-queue, causing it to only fire once.
By rotating the line of Impulse command blocks, the queue order from the redstone block is swapped and the Repeating block only fires once.
Use Chain blocks instead to guarantee activation order. See this paste to get a description of the queuing mechanic.
A similar issue was fixed recently. Is this still an issue in 15w44b? If so, please explain the issue in detail and provide steps to reproduce it.