automatics tests are broken

[kokarez]

The test on my last PR failed in a way that does not match the PR. Added to that, the error is the same than the last failed run on master.

My PR failure:

• https://travis-ci.org/xtensor-stack/xtensor-fftw/jobs/608699693?utm_medium=notification&utm_source=github_status

Last build on master:

• https://travis-ci.org/xtensor-stack/xtensor-fftw/builds/600631847

I may fix it if you dont before tomorrow (note Im in the US west coast so my schedule does not overlap with the main developer here)