Hayden K

I did some experimenting with this bug and found that it's direction dependent, the direction of the tripwire must be inline with the block offset to the side of the slime block, and the block must be on the south or west side of the slime block for the duplication to occur. If those conditions are not met the string will break as usual when the piston is extended and will not remain in place. Also of note the block offset from the slime block must be a solid block, when tried with glass in the same circumstances it simply broke the string as to be expected.

The bug also does not depend upon the redstone block block-update clock as shown in the screen shots, and in-fact doesn't require any timing whatsoever as you can cause the duplication using just a lever powering the sticky piston. It's also possible to stack up to 6 of these side by side using a single sticky piston, 6 slime blocks, and six solid blocks which results in a very efficient string farm, hence ripe for abuse.

Video demonstrating the cardinality of the design, powering with only a lever, and a sample string farm a player could construct using it (to show the issue): http://youtu.be/ykfbd07UYas

Didn`t realize that Creepers or Spiders had a shader. I just checked and it does exhibit the same bug for both of them.

Just tested this out in 13w09a and the bug still exists in it's reported form, even though the general comparators not getting updated by Hoppers bug (MC-9687) has been fixed.

Something I found while testing this myself was that it seems it might be affected by which way the repeaters are facing. (Due to the way redstone is updated each tick). I would like them to stay instant but I'm speculating that the way they checked for a looping comparator is taking up cpu time and causing these delays.