Fix CI in v4.0.x branch - #10810

self = <astropy.table.tests.test_index.TestIndex object at 0xefb2806c>
main_col = [1, 2, 3, 4, 5]
table_types = <astropy.table.tests.conftest.table_types.<locals>.TableTypes object at 0xefb28d8c>
engine = <class 'astropy.table.sorted_array.SortedArray'>

    def test_index_modes(self, main_col, table_types, engine):
        self._setup(main_col, table_types)
        t = self.t
        t.add_index('a', engine=engine)
    
        # first, no special mode
        assert len(t[[1, 3]].indices) == 1
        assert len(t[::-1].indices) == 1
        assert len(self._table_type(t).indices) == 1
        assert np.all(t.indices[0].sorted_data() == [0, 1, 2, 3, 4])
        t2 = t.copy()
    
        # non-copy mode
        with t.index_mode('discard_on_copy'):
            assert len(t[[1, 3]].indices) == 0
            assert len(t[::-1].indices) == 0
            assert len(self._table_type(t).indices) == 0
            assert len(t2.copy().indices) == 1  # mode should only affect t
    
        # make sure non-copy mode is exited correctly
        assert len(t[[1, 3]].indices) == 1
    
        if not self.mutable:
            return
    
        # non-modify mode
        with t.index_mode('freeze'):
            assert np.all(t.indices[0].sorted_data() == [0, 1, 2, 3, 4])
            t['a'][0] = 6
            assert np.all(t.indices[0].sorted_data() == [0, 1, 2, 3, 4])
            t.add_row((1.5, '12', 2))
            assert np.all(t.indices[0].sorted_data() == [0, 1, 2, 3, 4])
            t.remove_rows([1, 3])
            assert np.all(t.indices[0].sorted_data() == [0, 1, 2, 3, 4])
            assert_col_equal(t['a'], [6, 3, 5, 2])
            # mode should only affect t
            assert np.all(t2.indices[0].sorted_data() == [0, 1, 2, 3, 4])
            t2['a'][0] = 6
            assert np.all(t2.indices[0].sorted_data() == [1, 2, 3, 4, 0])
    
        # make sure non-modify mode is exited correctly
        assert np.all(t.indices[0].sorted_data() == [3, 1, 2, 0])
    
        if isinstance(t['a'], BaseColumn):
>           assert len(t['a'][::-1].info.indices) == 0

astropy/table/tests/test_index.py:368: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
astropy/utils/data_info.py:214: in __get__
    return getattr(instance._parent, self.attr)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <[AttributeError('failed access "info" attribute on a temporary object.\n\nIt looks like you have done something like ...ermanent\nreference with ``c = col[3:5]`` followed by ``c.info``.',) raised in repr()] ColumnInfo object at 0xefcecdc4>

        @property
        def _parent(self):
            try:
                parent = self._parent_ref()
            except AttributeError:
                return None
    
            if parent is None:
                raise AttributeError("""\
    failed access "info" attribute on a temporary object.
    
    It looks like you have done something like ``col[3:5].info``, i.e.
    you accessed ``info`` from a temporary slice object ``col[3:5]`` that
    only exists momentarily.  This has failed because the reference to
    that temporary object is now lost.  Instead force a permanent
>   reference with ``c = col[3:5]`` followed by ``c.info``.""")
E   AttributeError: failed access "info" attribute on a temporary object.
E   
E   It looks like you have done something like ``col[3:5].info``, i.e.
E   you accessed ``info`` from a temporary slice object ``col[3:5]`` that
E   only exists momentarily.  This has failed because the reference to
E   that temporary object is now lost.  Instead force a permanent
E   reference with ``c = col[3:5]`` followed by ``c.info``.

astropy/utils/data_info.py:321: AttributeError