Hopper still collects item entities when a container above it

Summary:

A hopper still catches item entities when a container attached to it above.

Steps to Reproduce:

1. Put a container above a hopper. 
2. Drop an item to that hopper.

 Or build like the screenshot below, then press the button.

Observed Results:

The item entity is collected by the hopper "successfully".

Expected Results:

A hopper with a container above it cannot collect dropped items.