Revert "patch ExtensionBlock fill_value, closes #27781, closes #29563 (#34158)"

This reverts commit a94b13a.

Author: TomAugspurger

doc/source/whatsnew/v1.1.0.rst

@@ -1130,7 +1130,6 @@ Sparse
 - Creating a :class:`SparseArray` from timezone-aware dtype will issue a warning before dropping timezone information, instead of doing so silently (:issue:`32501`)
 - Bug in :meth:`arrays.SparseArray.from_spmatrix` wrongly read scipy sparse matrix (:issue:`31991`)
 - Bug in :meth:`Series.sum` with ``SparseArray`` raises ``TypeError`` (:issue:`25777`)
-- Bug where :class:`DataFrame` containing :class:`SparseArray` filled with ``NaN`` when indexed by a list-like (:issue:`27781`, :issue:`29563`)
 - The repr of :class:`SparseDtype` now includes the repr of its ``fill_value`` attribute. Previously it used ``fill_value``'s  string representation (:issue:`34352`)
 - Bug where empty :class:`DataFrame` could not be cast to :class:`SparseDtype` (:issue:`33113`)
 - Bug in :meth:`arrays.SparseArray` was returning the incorrect type when indexing a sparse dataframe with an iterable (:issue:`34526`, :issue:`34540`)

pandas/core/internals/blocks.py

@@ -1636,10 +1636,7 @@ def _holder(self):
     @property
     def fill_value(self):
         # Used in reindex_indexer
-        if is_sparse(self.values):
-            return self.values.dtype.fill_value
-        else:
-            return self.values.dtype.na_value
+        return self.values.dtype.na_value
 
     @property
     def _can_hold_na(self):

pandas/tests/extension/base/getitem.py

@@ -399,31 +399,3 @@ def test_item(self, data):
 
         with pytest.raises(ValueError, match=msg):
             s.item()
-
-    def test_boolean_mask_frame_fill_value(self, data):
-        # https://github.com/pandas-dev/pandas/issues/27781
-        df = pd.DataFrame({"A": data})
-
-        mask = np.random.choice([True, False], df.shape[0])
-        result = pd.isna(df.iloc[mask]["A"])
-        expected = pd.isna(df["A"].iloc[mask])
-        self.assert_series_equal(result, expected)
-
-        mask = pd.Series(mask, index=df.index)
-        result = pd.isna(df.loc[mask]["A"])
-        expected = pd.isna(df["A"].loc[mask])
-        self.assert_series_equal(result, expected)
-
-    def test_fancy_index_frame_fill_value(self, data):
-        # https://github.com/pandas-dev/pandas/issues/29563
-        df = pd.DataFrame({"A": data})
-
-        mask = np.random.choice(df.shape[0], df.shape[0])
-        result = pd.isna(df.iloc[mask]["A"])
-        expected = pd.isna(df["A"].iloc[mask])
-        self.assert_series_equal(result, expected)
-
-        mask = pd.Series(mask, index=df.index)
-        result = pd.isna(df.loc[mask]["A"])
-        expected = pd.isna(df["A"].loc[mask])
-        self.assert_series_equal(result, expected)

pandas/tests/extension/test_sparse.py

@@ -41,11 +41,6 @@ def data_for_twos(request):
     return SparseArray(np.ones(100) * 2)
 
 
-@pytest.fixture(params=[0, np.nan])
-def data_zeros(request):
-    return SparseArray(np.zeros(100, dtype=int), fill_value=request.param)
-
-
 @pytest.fixture(params=[0, np.nan])
 def data_missing(request):
     """Length 2 array with [NA, Valid]"""