Mining blocks then mousing off keeps crack graphic in adventure mode

If I start breaking a block, and WHILE HOLDING LEFT CLICK, mouse off the block, the cracks still remain.

What I thought would happen:

When mousing off and holding left mouse, the cracks would disappear

What actually happened:

The cracks stayed

To reproduce

1. Go to adventure mode,

2. Place down a transparent and non transparent block.

3. Start breaking the transparent block and while holding down left mouse, move mouse over to non transparent block.

Untested on 1.8 snapshots. Testing now.

I have a video but its WAY to large: 383.36 MB