Redstone repeater looping on it's own

When a redstone signal is fed through a block, and then (with both repeaters on) the initial repeater is switched off, the second repeater will go crazy and start looping on it's own, without any redstone signals. This clearly wasn't the case in 14w25b. I don't know if this is normal but if it is this will affect a lot of redstone contraptions. (This happens in 14w26b)