redstone and detector rail bug

IF you have a detector rail and place redstone under it the redstone will permenetly receive power withought any source. example (top/detector rail/sandstone/redstone/sandtone/bottom)

What I expected to happen was...:
i place the redstone and it is off because there is no source

What actually happened was...:
permanently on like if there is a source.

Steps to Reproduce:
1. (Important: order counts : place detector rail first redstone second)
2. place detector rail on a block
3.under place redstone and watch it be magicly powered