update xfail

Author: jbrockmendel

pandas/tests/extension/test_string.py

@@ -260,7 +260,7 @@ def test_arith_series_with_array(
     def test_loc_setitem_with_expansion_preserves_ea_index_dtype(
         self, data, request, using_infer_string
     ):
-        if not using_infer_string:
+        if not using_infer_string and data.dtype.storage == "python":
             mark = pytest.mark.xfail(reason="Casts to object")
             request.applymarker(mark)
         super().test_loc_setitem_with_expansion_preserves_ea_index_dtype(data)