Mobs pathfind over magma blocks if a carpet is on top

Steps to Reproduce:

1. Make a 5 by 5 ring of magma blocks
2. Put a mob in the centre (ex. villager)
3. Put some carpet on top of the magma

Observed Results:

The mob walks over the carpet with magma beneath it.

Expected Results:

The mob doesn't walk over the magma.