Prepare next ipykernel

[davidbrochart]

ipykernel 6.0.0 will break our tests, see ipython/ipykernel#635 (comment).
We will need to update the cell outputs of our test notebooks.

[MSeal]

Thanks for digging into that -- it looks like we need to soften output error message matching in our tests? I think the new file path names will be randomized yes?

[davidbrochart]

Yes, it will be a random file path. I agree that we need to have these tests more tolerant.

[davidbrochart]

Now that ipython/ipykernel#652 is merged, tests should pass with ipykernel master if we set the following:

export IPYKERNEL_CELL_NAME="<IPY-INPUT>"

[davidbrochart]

Indeed, tests pass in #146. Let's get #147 in to prepare for ipykernel 6.0.