The latest snapshot changes some features about redstone dust, one of which i feel was intended to avoid behaviours such as this. Previously, blocks that would cause a redirection would not redirect the power to the piston below them. That was because redstone dust which was redirected would not power the block it was redirected towards, and therefore would not cause quasi-connectivity. Now, I suppose for the sake of visual consistency, this is not the case. This causes a piston that would redirect redstone towards it by means of a block such as a target block or powered rail to constantly pulse. I feel that this should not be the case, at least for upwards-facing pistons and target blocks, as what is causing the redirection is a solid block, and a piston would not be powered by the block above it. I understand that the reason for this is quasi-connectivity, but at the same time I feel like a constantly pulsing piston is neither a useful nor expected output.