Bug#1053700: python-xarray: autopkgtest regression on s390x

[Graham Inggs]

Source: python-xarray
Version: 2023.09.0-2
Severity: serious
User: debian-ci at lists.debian.org
Usertags: regression

Hi Maintainer

There are new autopkgtest failures on s390x [1] which seem to be
related to endianness, dtype('>M8[ns]') vs dtype('<M8[ns]').  I have
copied one of the failures from the log below, but there are more.

Regards
Graham


[1] https://ci.debian.net/packages/p/python-xarray/unstable/s390x/


207s _ test_roundtrip_datetime64_nanosecond_precision[1677-09-21T00:12:43.145224193-ns-int64-20-True]
_
207s
207s timestr = '1677-09-21T00:12:43.145224193', timeunit = 'ns'
207s dtype = <class 'numpy.int64'>, fill_value = 20, use_encoding = True
207s
207s     @pytest.mark.parametrize(
207s         "timestr, timeunit, dtype, fill_value, use_encoding",
207s         [
207s             ("1677-09-21T00:12:43.145224193", "ns", np.int64, 20, True),
207s             ("1970-09-21T00:12:44.145224808", "ns", np.float64,
1e30, True),
207s             (
207s                 "1677-09-21T00:12:43.145225216",
207s                 "ns",
207s                 np.float64,
207s                 -9.223372036854776e18,
207s                 True,
207s             ),
207s             ("1677-09-21T00:12:43.145224193", "ns", np.int64, None, False),
207s             ("1677-09-21T00:12:43.145225", "us", np.int64, None, False),
207s             ("1970-01-01T00:00:01.000001", "us", np.int64, None, False),
207s             ("1677-09-21T00:21:52.901038080", "ns", np.float32,
20.0, True),
207s         ],
207s     )
207s     def test_roundtrip_datetime64_nanosecond_precision(
207s         timestr: str,
207s         timeunit: str,
207s         dtype: np.typing.DTypeLike,
207s         fill_value: int | float | None,
207s         use_encoding: bool,
207s     ) -> None:
207s         # test for GH7817
207s         time = np.datetime64(timestr, timeunit)
207s         times = [np.datetime64("1970-01-01T00:00:00", timeunit),
np.datetime64("NaT"), time]
207s
207s         if use_encoding:
207s             encoding = dict(dtype=dtype, _FillValue=fill_value)
207s         else:
207s             encoding = {}
207s
207s         var = Variable(["time"], times, encoding=encoding)
207s >       assert var.dtype == np.dtype("<M8[ns]")
207s E       AssertionError: assert dtype('>M8[ns]') == dtype('<M8[ns]')
207s E        +  where dtype('>M8[ns]') = <xarray.Variable (time:
3)>\narray(['1970-01-01T00:00:00.000000000',
'NaT',\n       '1677-09-21T00:12:43.145224193'],
dtype='datetime64[ns]').dtype
207s E        +  and   dtype('<M8[ns]') = <class 'numpy.dtype'>('<M8[ns]')
207s E        +    where <class 'numpy.dtype'> = np.dtype