Cleanup: use is not instead of not ... is, etc.

[anntzer]

https://github.com/takluyver/astsearch is great for looking for patterns to fix :-)

[afvincent]

Wouldn't the CI failure be due to numpy issue #3322 (about array_equal)? All the failure tracebacks are similar to

File "/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/numpy/core/numeric.py", line 2119, in array_equal
    return bool(equal(a1,a2).all())
AttributeError: 'NotImplementedType' object has no attribute 'all'

[anntzer]

Yes, basically this needed numpy 1.8.0. Fixed now.

[NelleV]

I am pretty sure something is still wrong :)

[anntzer]

Bah, I just dropped that patch.

[NelleV]

@tacaswell We really need to set up appveyor so that the team is able to restart jobs.

[NelleV]

Closing and reopening for appveyor.

[QuLogic]

Something is weird in what actually got build on CI; I think a rebase is in order.

[anntzer]

Done (it rebased cleanly).