As shown in the pictures below, a target block does not stop redstone dust from connecting diagonally even though the target block is a solid block. 

This bug is solely visual and does not effect the redstone's behavior, since the target block still blocks the dust from getting powered.

At first i thought this was something with the texture pack I was using, but the visual bug still persisted.

How to reproduce:
1.) Place two blocks diagonally as shown in the image, and place redstone dust on top of them.
2.) place a target block above the dust on the lowest block as shown in the image. 
3.) power only the top line, and you should see that the bottom line stays unpowered, which is what should happen with other solid blocks.