Test failure with coordinates: 'NoneType' object has no attribute 'to_geodetic'

• Revert #11319

There is a test failure in coordinates in the 32bits job: 'NoneType' object has no attribute 'to_geodetic' https://github.com/astropy/astropy/pull/11274/checks?check_run_id=1772534200

_______________ test_skyoffset[inradec0-expectedlatlon0-tolsep0] _______________

inradec = <Quantity [45., 45.] deg>, expectedlatlon = <Quantity [0., 0.] deg>
tolsep = <Quantity 0.001 arcsec>, originradec = <Quantity [45., 45.] deg>

    @pytest.mark.parametrize("inradec,expectedlatlon, tolsep", [
        ((45, 45)*u.deg, (0, 0)*u.deg, .001*u.arcsec),
        ((45, 0)*u.deg, (0, -45)*u.deg, .001*u.arcsec),
        ((45, 90)*u.deg, (0, 45)*u.deg, .001*u.arcsec),
        ((46, 45)*u.deg, (1*np.cos(45*u.deg), 0)*u.deg, 16*u.arcsec),
        ])
    def test_skyoffset(inradec, expectedlatlon, tolsep, originradec=(45, 45)*u.deg):
        origin = ICRS(*originradec)
        skyoffset_frame = SkyOffsetFrame(origin=origin)
    
        skycoord = SkyCoord(*inradec, frame=ICRS)
        skycoord_inaf = skycoord.transform_to(skyoffset_frame)
        assert hasattr(skycoord_inaf, 'lon')
        assert hasattr(skycoord_inaf, 'lat')
        expected = SkyCoord(*expectedlatlon, frame=skyoffset_frame)
    
        assert skycoord_inaf.separation(expected) < tolsep
        # Check we can also transform back (regression test for gh-11254).
>       roundtrip = skycoord_inaf.transform_to(ICRS())

../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/tests/test_skyoffset_transformations.py:33: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/sky_coordinate.py:627: in transform_to
    return self.__class__(new_coord, **frame_kwargs)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/sky_coordinate.py:323: in __init__
    setattr(self, attr, skycoord_kwargs[attr])
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/sky_coordinate.py:811: in __setattr__
    frame_transform_graph.frame_attributes[attr].__get__(self)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/attributes.py:104: in __get__
    out, converted = self.convert_input(out)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/attributes.py:451: in convert_input
    transformedobj = value.transform_to(self._frame)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/sky_coordinate.py:619: in transform_to
    new_coord = trans(self.frame, generic_frame)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/transformations.py:1422: in __call__
    curr_coord = t(curr_coord, curr_toframe)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/transformations.py:1025: in __call__
    return supcall(fromcoord, toframe)
../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/builtin_frames/icrs_observed_transforms.py:29: in icrs_to_altaz
    astrom = erfa_astrom.get().apco(altaz_frame)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

frame_or_coord = <AltAz Frame (obstime=None, location=None, pressure=0.0 hPa, temperature=0.0 deg_C, relative_humidity=0.0, obswl=1.0 micron)>

    @staticmethod
    def apco(frame_or_coord):
        '''
        Wrapper for ``erfa.apco``, used in conversions AltAz <-> ICRS and CIRS <-> ICRS
    
        Arguments
        ---------
        frame_or_coord: ``astropy.coordinates.BaseCoordinateFrame`` or ``astropy.coordinates.SkyCoord``
            Frame or coordinate instance in the corresponding frame
            for which to calculate the calculate the astrom values.
            For this function, an AltAz or CIRS frame is expected.
        '''
>       lon, lat, height = frame_or_coord.location.to_geodetic('WGS84')
E       AttributeError: 'NoneType' object has no attribute 'to_geodetic'

../../.tox/py38-test-double/lib/python3.8/site-packages/astropy/coordinates/erfa_astrom.py:45: AttributeError

[mhvk]

The problem is that the error is actually wrong: it is using the origin instance for a different OffsetFrame than the one that is passed in. It could happen in user code too (if they have offset frames in different coordinate systems).

p.s. I do think we could have a relatively hacky work-around, but need to have some time to think it through.

[mhvk]

Yikes, this is tricky: I cannot consistently reproduce getting the error on the 2nd run with your one-liner calling astropy.test twice. The first time I tried, it worked, but now tried a few times again and both calls just pass. Well, at least perhaps that is what happened to your cache clearing too?!