error when quantifying a dimension

[keewis]

Trying to quantify a DataArray describing a dimension after pulling it out fails:

In [2]: ds = xr.Dataset(coords={"x": ("x", [0, 1], {"units": "m"}), "y": ("y", [5, 6, 7], {"units": "m"})})
   ...: ds
Out[2]: 
<xarray.Dataset>
Dimensions:  (x: 2, y: 3)
Coordinates:
  * x        (x) int64 0 1
  * y        (y) int64 5 6 7
Data variables:
    *empty*

In [3]: q = ds.pint.quantify()
   ...: q
Out[3]: 
<xarray.Dataset>
Dimensions:  (x: 2, y: 3)
Coordinates:
  * x        (x) int64 0 1
  * y        (y) int64 5 6 7
Data variables:
    *empty*

In [4]: q.x
Out[4]: 
<xarray.DataArray 'x' (x: 2)>
array([0, 1])
Coordinates:
  * x        (x) int64 0 1
Attributes:
    units:    meter

In [5]: q.x.pint.quantify()
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-5-ac870069d90f> in <module>
----> 1 q.x.pint.quantify()

.../pint_xarray/accessors.py in quantify(self, units, unit_registry, **unit_kwargs)
    317         units = either_dict_or_kwargs(units, unit_kwargs, "quantify")
    318 
--> 319         registry = get_registry(unit_registry, units, conversion.extract_units(self.da))
    320 
    321         unit_attrs = conversion.extract_unit_attributes(self.da)

.../pint_xarray/conversion.py in extract_units(obj)
    248         name = obj.name if obj.name is not None else "<this-array>"
    249 
--> 250         ds = obj.rename(name).to_dataset()
    251 
    252         units = extract_units(ds)

.../xarray/core/dataarray.py in to_dataset(self, dim, name, promote_attrs)
    576             result = self._to_dataset_split(dim)
    577         else:
--> 578             result = self._to_dataset_whole(name)
    579 
    580         if promote_attrs:

.../xarray/core/dataarray.py in _to_dataset_whole(self, name, shallow_copy)
    525             )
    526         if name in self.coords:
--> 527             raise ValueError(
    528                 "cannot create a Dataset from a DataArray with "
    529                 "the same name as one of its coordinates"

ValueError: cannot create a Dataset from a DataArray with the same name as one of its coordinates

We should try to fix this.