The CRON job starts to fail due to a recent pull-request merged in NumPy. The error is the following:

DeprecationWarning: Creating an ndarray with automatic 
object dtype is deprecated, use dtype=object if you intended
it, otherwise specify an exact dtype

Therefore, we need to go through the lines and edit the np.array() call to add dtype=object. To know which tests are failing, one can look at the log on the CRON job (e.g. https://travis-ci.org/scikit-learn/scikit-learn/builds/620654456).

Be aware that you need NumPy master (or the nighlty build) to get the error.