Complete deprecations finishing in 0.21

$ git grep -w "0\.21" 'sklearn/*.py'
sklearn/cluster/hierarchical.py:                      "will be removed in 0.21", DeprecationWarning)
sklearn/covariance/graph_lasso_.py:                "will be removed in 0.21. Use ``grid_scores_`` instead")
sklearn/covariance/tests/test_graph_lasso.py:                    "0.19 and will be removed in 0.21. Use "
sklearn/covariance/tests/test_graphical_lasso.py:                    "0.19 and will be removed in 0.21. Use "
sklearn/datasets/mlcomp.py:            "in version 0.19 and will be removed in 0.21.")
sklearn/decomposition/fastica_.py:               This parameter will be removed in 0.21.
sklearn/decomposition/fastica_.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/decomposition/online_lda.py:        be removed in version 0.21.
sklearn/decomposition/online_lda.py:                          "version 0.19 and will be removed in 0.21",
sklearn/decomposition/online_lda.py:                          "argument will be removed in 0.21.",
sklearn/decomposition/sparse_pca.py:               This parameter will be removed in 0.21.
sklearn/decomposition/sparse_pca.py:                          "deprecated since 0.19 and will be removed in 0.21. "
sklearn/discriminant_analysis.py:                " 0.19 and will be removed in 0.21. Use "
sklearn/discriminant_analysis.py:                          " in version 0.19 and will be removed in 0.21.",
sklearn/ensemble/forest.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/forest.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/forest.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/forest.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/forest.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/gradient_boosting.py:                "will be removed in 0.21.")
sklearn/ensemble/gradient_boosting.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/gradient_boosting.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/ensemble/tests/test_voting_classifier.py:                "changed to True in 0.21. "
sklearn/ensemble/voting_classifier.py:                              "changed to True in 0.21. "
sklearn/feature_extraction/hashing.py:            This option will be removed in 0.21.
sklearn/feature_extraction/hashing.py:                          " in version 0.21.", DeprecationWarning)
sklearn/feature_extraction/text.py:            This option will be removed in 0.21.
sklearn/gaussian_process/gpr.py:                "will be removed in 0.21.")
sklearn/gaussian_process/gpr.py:                "will be removed in 0.21.")
sklearn/kernel_approximation.py:                    " raise an error in 0.21, as they are ignored. Use "
sklearn/linear_model/least_angle.py:                "will be removed in 0.21. See ``alpha_`` instead")
sklearn/linear_model/passive_aggressive.py:        Defaults to 5. Defaults to 1000 from 0.21, or if tol is not None.
sklearn/linear_model/passive_aggressive.py:        Defaults to 1e-3 from 0.21.
sklearn/linear_model/passive_aggressive.py:        Defaults to None. Deprecated, will be removed in 0.21.
sklearn/linear_model/passive_aggressive.py:        Defaults to 5. Defaults to 1000 from 0.21, or if tol is not None.
sklearn/linear_model/passive_aggressive.py:        Defaults to 1e-3 from 0.21.
sklearn/linear_model/passive_aggressive.py:        Defaults to None. Deprecated, will be removed in 0.21.
sklearn/linear_model/perceptron.py:        Defaults to 5. Defaults to 1000 from 0.21, or if tol is not None.
sklearn/linear_model/perceptron.py:        Defaults to 1e-3 from 0.21.
sklearn/linear_model/perceptron.py:        Defaults to None. Deprecated, will be removed in 0.21.
sklearn/linear_model/randomized_l1.py:            " and will be removed in 0.21.")
sklearn/linear_model/randomized_l1.py:            " and will be removed in 0.21.")
sklearn/linear_model/randomized_l1.py:            " and will be removed in 0.21.")
sklearn/linear_model/randomized_l1.py:            " and will be removed in 0.21.")
sklearn/linear_model/stochastic_gradient.py:                          " removed in 0.21. Use max_iter and tol instead.",
sklearn/linear_model/stochastic_gradient.py:                    "From 0.21, default max_iter will be 1000, and"
sklearn/linear_model/stochastic_gradient.py:                "will be removed in 0.21. Use ``loss_function_`` instead")
sklearn/linear_model/stochastic_gradient.py:        Defaults to 5. Defaults to 1000 from 0.21, or if tol is not None.
sklearn/linear_model/stochastic_gradient.py:        Defaults to 1e-3 from 0.21.
sklearn/linear_model/stochastic_gradient.py:        Defaults to None. Deprecated, will be removed in 0.21.
sklearn/linear_model/stochastic_gradient.py:        Defaults to 5. Defaults to 1000 from 0.21, or if tol is not None.
sklearn/linear_model/stochastic_gradient.py:        Defaults to 1e-3 from 0.21.
sklearn/linear_model/stochastic_gradient.py:        Defaults to None. Deprecated, will be removed in 0.21.
sklearn/linear_model/tests/test_randomized_l1.py:                         "deprecated in 0.19 and will be removed in 0.21.",
sklearn/linear_model/tests/test_randomized_l1.py:                         "deprecated in 0.19 and will be removed in 0.21.",
sklearn/linear_model/tests/test_randomized_l1.py:                         "deprecated in 0.19 and will be removed in 0.21.",
sklearn/linear_model/tests/test_sgd.py:    # Test that warnings are raised. Will be removed in 0.21
sklearn/manifold/t_sne.py:                "will be removed in 0.21. Use ``n_iter_`` instead")
sklearn/metrics/pairwise.py:                      '0.21 of scikit-learn', DeprecationWarning)
sklearn/model_selection/_search.py:                          'in version 0.21. Pass fit parameters to the '
sklearn/model_selection/_search.py:        # TODO: replace by a dict in 0.21
sklearn/model_selection/_search.py:                            'any more in 0.21. If you need training scores, '
sklearn/model_selection/_search.py:           0.19 and will be removed in version 0.21. Pass fit parameters to
sklearn/model_selection/_search.py:        will change to False in version 0.21, to correspond to the standard
sklearn/model_selection/_search.py:        That default will be changed to ``False`` in 0.21.
sklearn/model_selection/_search.py:           0.19 and will be removed in version 0.21. Pass fit parameters to
sklearn/model_selection/_search.py:        will change to False in version 0.21, to correspond to the standard
sklearn/model_selection/_search.py:        That default will be changed to ``False`` in 0.21.
sklearn/model_selection/_split.py:        The default will change in version 0.21. It will remain 0.1 only
sklearn/model_selection/_split.py:        The default will change in version 0.21. It will remain 0.2 only
sklearn/model_selection/_split.py:                warnings.warn("From version 0.21, test_size will always "
sklearn/model_selection/_split.py:        The default will change in version 0.21. It will remain 0.1 only
sklearn/model_selection/_split.py:            warnings.warn("From version 0.21, test_size will always "
sklearn/model_selection/_split.py:        The default will change in version 0.21. It will remain 0.25 only
sklearn/model_selection/_split.py:            warnings.warn("From version 0.21, test_size will always "
sklearn/model_selection/_validation.py:        That default will be changed to ``False`` in 0.21.
sklearn/model_selection/_validation.py:    # TODO: replace by a dict in 0.21
sklearn/model_selection/_validation.py:                    'any more in 0.21. If you need training scores, '
sklearn/model_selection/tests/test_search.py:    # Test that warnings are raised. Will be removed in 0.21
sklearn/model_selection/tests/test_search.py:            'any more in 0.21. If you need training scores, '
sklearn/model_selection/tests/test_validation.py:    # Test that warnings are raised. Will be removed in 0.21
sklearn/model_selection/tests/test_validation.py:        'any more in 0.21. If you need training scores, '
sklearn/neighbors/approximate.py:                      "in 0.19. It will be removed in version 0.21.",
sklearn/neighbors/tests/test_approximate.py:                         "in version 0.21.", LSHForest)
sklearn/preprocessing/__init__.py:# stub, remove in version 0.21
sklearn/preprocessing/_function_transformer.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/_function_transformer.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/_function_transformer.py:                          "will be removed in 0.21", DeprecationWarning)
sklearn/preprocessing/data.py:               This parameter will be removed in 0.21.
sklearn/preprocessing/data.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/data.py:               This parameter will be removed in 0.21.
sklearn/preprocessing/data.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/data.py:               This parameter will be removed in 0.21.
sklearn/preprocessing/data.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/data.py:               This parameter will be removed in 0.21.
sklearn/preprocessing/data.py:                          "deprecated since 0.19 and will be removed in 0.21",
sklearn/preprocessing/data.py:    This stub will be removed in version 0.21.
sklearn/preprocessing/data.py:            "This stub will be removed in version 0.21.")
sklearn/semi_supervised/label_propagation.py:            This parameter will be removed in 0.21.
sklearn/semi_supervised/label_propagation.py:                "alpha is deprecated since 0.19 and will be removed in 0.21.",
sklearn/tests/test_discriminant_analysis.py:                         "removed in 0.21.", clf.fit, X, y)
sklearn/tests/test_discriminant_analysis.py:                         "in 0.21. Use ``covariance_`` instead", getattr, clf,
sklearn/tree/tree.py:                          " will be removed in version 0.21. "
sklearn/tree/tree.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/tree/tree.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/tree/tree.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/tree/tree.py:           ``min_impurity_decrease`` in 0.19 and will be removed in 0.21.
sklearn/utils/arpack.py:# Remove this module in version 0.21
sklearn/utils/arpack.py:            "will be removed in 0.21. Use scipy.sparse.linalg.eigs instead.")
sklearn/utils/arpack.py:            "will be removed in 0.21. Use scipy.sparse.linalg.eigsh instead.")
sklearn/utils/arpack.py:            "will be removed in 0.21. Use scipy.sparse.linalg.svds instead.")
sklearn/utils/estimator_checks.py:                # To remove in 0.21, when they get their future default values
sklearn/utils/extmath.py:            "and will be removed in 0.21. Use scipy.linalg.norm instead.")
sklearn/utils/extmath.py:            "and will be removed in 0.21. Use the equivalent np.dot instead.")
sklearn/utils/extmath.py:            "and will be removed in 0.21. Use scipy.misc.logsumexp instead.")
sklearn/utils/extmath.py:            "and will be removed in 0.21. Use scipy.linalg.pinvh instead.")
sklearn/utils/graph.py:            "version 0.19 and will be removed in 0.21. Use "
sklearn/utils/graph.py:            "0.19 and will be removed in 0.21. Use "
sklearn/utils/random.py:            "and will be removed in 0.21. Use np.random.choice or "
sklearn/utils/sparsetools/__init__.py:# Remove in version 0.21
sklearn/utils/sparsetools/__init__.py:            "version 0.19 and will be removed in 0.21. Use "
sklearn/utils/sparsetools/setup.py:# Remove in version 0.21
sklearn/utils/stats.py:# Remove in sklearn 0.21
sklearn/utils/stats.py:            "will be removed in 0.21. Use scipy.stats.rankdata instead.")
sklearn/utils/tests/test_extmath.py:@ignore_warnings  # Test deprecated backport to be removed in 0.21
sklearn/utils/tests/test_extmath.py:@ignore_warnings  # extmath.norm is deprecated to be removed in 0.21
sklearn/utils/tests/test_stats.py:    # Test deprecated backport to be removed in 0.21
sklearn/utils/tests/test_utils.py:@ignore_warnings  # Test deprecated backport to be removed in 0.21
sklearn/utils/tests/test_utils.py:@ignore_warnings  # Test deprecated backport to be removed in 0.21
sklearn/utils/tests/test_utils.py:@ignore_warnings  # Test deprecated backport to be removed in 0.21
sklearn/utils/tests/test_utils.py:@ignore_warnings  # Test deprecated backport to be removed in 0.21
sklearn/utils/validation.py:           deprecated in version 0.19 "and will be removed in 0.21. Use
sklearn/utils/validation.py:            "and will be removed in 0.21. Use 'accept_sparse=False' "
sklearn/utils/validation.py:           deprecated in version 0.19 "and will be removed in 0.21. Use

[amueller]

(if I have time I’ll do this just for the satisfaction of deleting so much code, as usual 😉

[adrinjalali]

I think this is done.