Pausing the game doesnt pause entities

ive found a realy big bug in the 13w41a, if you pause the game entities look to be paused but when you unpause it the entities all move jump to a new spot, also happens with items traveling through hoppers and redstone, when you pause then game the look to have stopped then a massive surge of items flow through hoppers, its had to explain but if you do some fast tests you will see the problem