Fix failing sklearn test (#3850)

Author: schlunma

tests/integration/diag_scripts/mlr/test_custom_sklearn_functions.py

@@ -42,7 +42,6 @@
 # pylint: disable=too-few-public-methods
 # pylint: disable=too-many-arguments
 
-import warnings
 from copy import copy, deepcopy
 
 import numpy as np
@@ -505,9 +504,7 @@ def test_is_pairwise():
     """Test ``_is_pairwise``."""
     # Simple checks for _is_pairwise
     pca = KernelPCA(kernel='precomputed')
-    with warnings.catch_warnings():
-        warnings.simplefilter("error")  # make sure that no warning is raised
-        assert _is_pairwise(pca)
+    assert _is_pairwise(pca)
 
     # Pairwise attribute that is not consistent with the pairwise tag
     class IncorrectTagPCA(KernelPCA):
@@ -533,9 +530,7 @@ class TruePairwise(BaseEstimator):
 
     # Pairwise attribute is not defined thus tag is used
     est = BaseEstimator()
-    with warnings.catch_warnings():
-        warnings.simplefilter("error")  # make sure that no warning is raised
-        assert not _is_pairwise(est)
+    assert not _is_pairwise(est)
 
 
 # _safe_split