Nightlies (MacOSX) are failing because of this one

Segmentation fault :-|

https://gitlab.idiap.ch/bob/bob.nightlies/-/jobs/151320

+ nosetests --with-coverage --cover-package=bob.learn.boosting -sv bob.learn.boosting
test01_stump_boosting (bob.learn.boosting.tests.test_boosting.TestBoosting) ... Starting 1 rounds of boosting
Starting round 1
Finished round 1 / 1
/Users/gitlab/builds/b6d3167a/0/bob/bob.nightlies/miniconda/conda-bld/bob.learn.boosting_1540886930750/test_tmp/run_test.sh: line 8: 42994 Segmentation fault: 11  nosetests --with-coverage --cover-package=bob.learn.boosting -sv bob.learn.boosting
Tests failed for bob.learn.boosting-2.0.16b0-py36ha733eee_11.tar.bz2 - moving package to /Users/gitlab/builds/b6d3167a/0/bob/bob.nightlies/miniconda/conda-bld/broken
WARNING:conda_build.build:Tests failed for bob.learn.boosting-2.0.16b0-py36ha733eee_11.tar.bz2 - moving package to /Users/gitlab/builds/b6d3167a/0/bob/bob.nightlies/miniconda/conda-bld/broken
TESTS FAILED: bob.learn.boosting-2.0.16b0-py36ha733eee_11.tar.bz2
(09:11:43.089) Error: Command Failed "/Users/gitlab/builds/b6d3167a/0/bob/bob.nightlies/miniconda/bin/conda build --no-anaconda-upload --variant-config-files /Users/gitlab/builds/b6d3167a/0/bob/bob.nightlies/src/bob.learn.boosting/_ci/conda_build_config.yaml --python=3.6 conda"
(09:11:43.095) Error: Command Failed "./_ci/build.sh"
(09:11:43.102) Error: Package bob.learn.boosting rebuild FAILED - aborting...