While playing with sticky pistons, I discovered a glitch that treats the piston arm as a solid block! (by solid I mean not transparent)

To make it, you do this:

aaaara
oabpbr
bbtbbb

a= air, r= redstone wire, o=obsidian, b=any block, p= piston, and t=redstone torch.

connect piston to yellow highlighted b, and you have a rapidly repeating piston!

But for the glitch to occur, you must place an obsidian block on red highlighted air block, which activates the glitch.

I cannot really explain the glitch, unfortunately. It would really help if i knew why it happens.