Pickaxe won't mine while attack indicator is recharging

The bug

If you 'attack' air and then move to a block to mine, the pick wont instantly start to mine it, only after the attack indicator has almost run out.

How to reproduce

Hit air besides a block and then move to a block. This appears to happen for all tools, and it only seems to happen when you hold your mouse button after attacking, not when you click to attack and then try to mine.