Sniffers freeze while searching when bumping into blocks

The Bug:

Sniffers freeze while searching when bumping into blocks.

Steps to Reproduce:

1. Summon a sniffer on some grass blocks and wait for it to begin searching.
2. As soon as it begins sniffing the ground and tilting its head side to side, place a block in front of it.
3. Observe the sniffer's behavior for a while.
4. Take note as to whether or not sniffers freeze while searching when bumping into blocks.

Observed Behavior:

Sniffers freeze.

Expected Behavior:

Sniffers would not freeze.