Piston Not Turning Off

Okay, this is how the bug is, heres what it would look R = Redstone Block, P = Sticky Piston, T = Redstone Torch. How it works is the redstone block is on the TOP. And the piston is un-powered, once powered It actually DOESN'T turn off, even if you destroy the torch. Once you cause a block update (E,I destroy the redstone block) Thank You very much for reading!
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R
P T