Chains are rendered too dark when blocks are placed adjacent to them while smooth lighting is enabled

The Bug:

Chains are rendered too dark when blocks are placed adjacent to them while smooth lighting is enabled.

This is not the shadow cast by the blocks, the chain actually is rendered darker.

Steps to Reproduce:

1. Enable smooth lighting and place down a sideways-facing chain.

2. Place blocks all around the chain.

3. Take note as to whether or not chains are rendered too dark when blocks are placed adjacent to them while smooth lighting is enabled.

Observed Behavior:

Chains are rendered too dark.

Expected Behavior:

Chains would not be rendered too dark.