xarray: more upstream-dev cftime failures

https://dev.azure.com/xarray/xarray/_build/results?buildId=2116&view=logs&jobId=2280efed-fda1-53bd-9213-1fa8ec9b4fa8&j=2280efed-fda1-53bd-9213-1fa8ec9b4fa8&t=175181ee-1928-5a6b-f537-168f7a8b7c2d

46 failed tests but they all seem to result from the same TypeError

=================================== FAILURES ===================================
______________ test_sel_date_scalar_nearest[365_day-sel_kwargs0] _______________

da = <xarray.DataArray (time: 4)>
             0002-02-01 00:00:00],
            dtype='object')
sel_kwargs = {'method': 'nearest'}

    @requires_cftime
    @pytest.mark.parametrize(
        "sel_kwargs",
        [{"method": "nearest"}, {"method": "nearest", "tolerance": timedelta(days=70)}],
    )
    def test_sel_date_scalar_nearest(da, date_type, index, sel_kwargs):
        expected = xr.DataArray(2).assign_coords(time=index[1])
>       result = da.sel(time=date_type(1, 4, 1), **sel_kwargs)

xarray/tests/test_cftimeindex.py:460: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
xarray/core/dataarray.py:1056: in sel
    ds = self._to_temp_dataset().sel(
xarray/core/dataset.py:2056: in sel
    pos_indexers, new_indexes = remap_label_indexers(
xarray/core/coordinates.py:391: in remap_label_indexers
    pos_indexers, new_indexes = indexing.remap_label_indexers(
xarray/core/indexing.py:270: in remap_label_indexers
    idxr, new_idx = convert_label_indexer(index, label, dim, method, tolerance)
xarray/core/indexing.py:189: in convert_label_indexer
    indexer = index.get_loc(
xarray/coding/cftimeindex.py:334: in get_loc
    return pd.Index.get_loc(self, key, method=method, tolerance=tolerance)
/usr/share/miniconda/envs/xarray-tests/lib/python3.8/site-packages/pandas/core/indexes/base.py:2899: in get_loc
    indexer = self.get_indexer([key], method=method, tolerance=tolerance)
/usr/share/miniconda/envs/xarray-tests/lib/python3.8/site-packages/pandas/core/indexes/base.py:2992: in get_indexer
    indexer = self._get_nearest_indexer(target, limit, tolerance)
/usr/share/miniconda/envs/xarray-tests/lib/python3.8/site-packages/pandas/core/indexes/base.py:3076: in _get_nearest_indexer
    left_distances = np.abs(self[left_indexer] - target)
xarray/coding/cftimeindex.py:444: in __sub__
    return CFTimeIndex(np.array(self) - other)
xarray/coding/cftimeindex.py:248: in __new__
    assert_all_valid_date_type(data)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

data = TimedeltaIndex(['-59 days'], dtype='timedelta64[ns]', freq=None)

    def assert_all_valid_date_type(data):
        import cftime
    
        if len(data) > 0:
            sample = data[0]
            date_type = type(sample)
            if not isinstance(sample, cftime.datetime):
>               raise TypeError(
                    "CFTimeIndex requires cftime.datetime "
                    "objects. Got object of {}.".format(date_type)
                )
E               TypeError: CFTimeIndex requires cftime.datetime objects. Got object of <class 'pandas._libs.tslibs.timedeltas.Timedelta'>.

xarray/coding/cftimeindex.py:206: TypeError