Double Piston Extenders cause clipping upon final extension of the piston

The Bug:
Double Piston Extenders (Both vertical and horizontal) cause the player to clip into the block being pushed by the extender after the second piston extends. Extended delay does not fix the problem. This does not apply to single piston extensions.

Steps to Reproduce:

• Build the setup shown in the attachment below:
  

  [media]

• Stand on the stone block pictured in the setup image and flick the lever.

Observed Behavior:
The player phases into iron block upon the extension of the second and final piston.
(See PistonExtender.mp4)

Expected Behavior:
The player should be pushed along by the iron block by 2 blocks instead of phasing through.