sklearn.tests.test_common.check_transformer_general(Imputer) ... /home/andy/checkout/scikit-learn/sklearn/preprocessing/imputation.py:341: VisibleDeprecationWarning: boolean index did not match indexed array along dimension 0; dimension is 30 but corresponding boolean dimension is 3
missing = np.arange(X.shape[not self.axis])[invalid_mask]

This is omnious.