Snow layer isn't supposed to appear on packed ice, but occasionally it happens during terrain generation.

Reproduction:
Not really possible to reproduce because it happens during terrain
generation.

I can give a location + seed where it happens (see attached screenshots):
Seed: 4768779715342538054
Coordinates: X -168, Y 72, Z 2317

Versions affected:
The same spot in 1.7.4 does not have packed ice at that location, so I suspect a change in the recent snapshots is causing this. It does seem very rare though, haven't found a second recreatable example of it. I've seen it on 2 other places when recreating this seed, but those spots did not generate a snow layer consistently.
I did not check other snapshots to see where this started occuring, only observed it in 14w04b.

Behavior:
It does seem like the game/terrain updates itself when you try removing the snow layer above any of the packed ice as the snow layers on the other packed ice will be removed as well. This only results in 1 snowball.