Test failing on OSX

[bluescarni]

A graph test is failing on the OSX conda-forge pipeline. The test is test-graph-multicut-greedy-additive. I have added some debug output to the test, see the patch here:

https://github.com/conda-forge/staged-recipes/pull/2807/files#diff-5f7894804b06e6bb15d1ca73db6353d5R1

With the output debug enabled, this is the screen output of the test:

https://travis-ci.org/conda-forge/staged-recipes/builds/220550265#L553