Revert "CLN: Remove special cases in indexing ops (pandas-dev#52063)"

This reverts commit 8e456d3.

Author: matiaslindgren

pandas/core/indexing.py

@@ -810,8 +810,14 @@ def _maybe_mask_setitem_value(self, indexer, value):
 
                 if is_scalar_indexer(icols, self.ndim - 1) and ndim == 1:
                     # e.g. test_loc_setitem_boolean_mask_allfalse
-                    # test_loc_setitem_ndframe_values_alignment
-                    value = self.obj.iloc._align_series(indexer, value)
+                    if len(newkey) == 0:
+                        # FIXME: kludge for test_loc_setitem_boolean_mask_allfalse
+                        # TODO(GH#45333): may be fixed when deprecation is enforced
+
+                        value = value.iloc[:0]
+                    else:
+                        # test_loc_setitem_ndframe_values_alignment
+                        value = self.obj.iloc._align_series(indexer, value)
                     indexer = (newkey, icols)
 
                 elif (
@@ -827,8 +833,14 @@ def _maybe_mask_setitem_value(self, indexer, value):
                         indexer = (newkey, icols)
 
                     elif ndim == 2 and value.shape[1] == 1:
-                        # test_loc_setitem_ndframe_values_alignment
-                        value = self.obj.iloc._align_frame(indexer, value)
+                        if len(newkey) == 0:
+                            # FIXME: kludge for
+                            #  test_loc_setitem_all_false_boolean_two_blocks
+                            #  TODO(GH#45333): may be fixed when deprecation is enforced
+                            value = value.iloc[:0]
+                        else:
+                            # test_loc_setitem_ndframe_values_alignment
+                            value = self.obj.iloc._align_frame(indexer, value)
                         indexer = (newkey, icols)
         elif com.is_bool_indexer(indexer):
             indexer = indexer.nonzero()[0]
@@ -2389,7 +2401,7 @@ def ravel(i):
                         new_ix = Index([new_ix])
                     else:
                         new_ix = Index(new_ix)
-                    if ser.index.equals(new_ix):
+                    if ser.index.equals(new_ix) or not len(new_ix):
                         if using_cow:
                             return ser
                         return ser._values.copy()