Redstone torches popping off causing unpowered repeaters to pulse every redstone tick.

What I expected to happen was...:
I placed a redstone block using /setblock to activate a set of command blocks, then replaced the redstone block with stone to switch to another set of commands. in 14w21b, this machine worked.

What actually happened was...:
after the stone was placed, the redstone torch that the redstone block used to power popped off. It had not been attached directly to the redstone block/stone. The furthest of the pair of repeaters that had been directly powered by the redstone torch began to pulse each redstone tick even though the repeater directly behind it was off.

Steps to Reproduce:
I could not figure out how to reproduce it. sorry.. I had five separate machines with the same redstone and only two of them did this.

This was happening on a vanilla server that I administrate.

Even though i could not replicate the bug, i have added a picture that shows the machine's actions.