Fix .test() on ddp

[williamFalcon]

This might be broken on notebooks only.
#875 solves a few problems with .test()

However, ddp + .test might be broken on notebooks because of the "spawn" option. (likely #747).

[williamFalcon]

Anyone interested in looking at this?
@Borda

[sneiman]

I am investigating this. Thats how I ran into the spawn issue with shared Q's. I am not using a notebook. This is (I believe) because ddp reduces tensors and parameters back to dev_ids[0] and there is no obvious way to get them back to the spawning CPU. I am slowly making progress, but don't have a lot of consistent time to put in.

[s-rog]

Isn't ddp broken in notebooks in the first place?