Comparator only graphical redstone flickering.

When having a comperator set up as in the attachment, the redstone flickers, but it doesn't affect pistons, redstone torches etc. Pistons and other redstone items only detect the redstone signal as being turned on.

I also made a recording for this bug, you can find it here: http://youtu.be/fDL55-lTAjU

I am aware that there are bugs reported about the comparator not being updated, but this bug is also about the redstone turning off and on.

This is on the 1.5 Pre-Release.