issues: 626063031

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
626063031 MDU6SXNzdWU2MjYwNjMwMzE= 4101 reset_index does not keep attributes 23738400 closed 0     1 2020-05-27T22:01:09Z 2020-06-05T19:39:10Z 2020-06-05T19:39:10Z CONTRIBUTOR      

If an indexing coordinate with attributes is converted to a non indexing coordinate with reset_index, the attributes are lost. I am not sure it is a bug, but I think they should keep the attributes and reset_coords does keep the attributes of reset coordinates.

MCVE Code Sample

```python temp = 15 + 8 * np.random.randn(2, 2, 3) time = xr.DataArray(pd.date_range('2014-09-06', periods=3), dims=["time"]).assign_attrs({"attr": 23}) coord = xr.DataArray([[-99.83, -99.32], [-99.79, -99.23]], dims=["x", "y"]).assign_attrs({"coord": True})

ds = xr.Dataset( { 'temperature': (['x', 'y', 'time'], temp), }, coords={ 'coord_0': coord, 'time': time, } ) ds

both coord_0 and time have attributes

ds.reset_index("time")

coordinate time_ does not have attributes anymore

ds.reset_coords("coord_0")

data variable coord_0 still has attributes

```

Expected Output

I would expect attributes to be kept.

Possible solution

I was wondering if changing this line and this other line to

vars_to_create[str(d) + "_"] = Variable(d, index, variables[d].attrs)

could solve this. If so I'll send a PR whenever I can.

Versions

Output of <tt>xr.show_versions()</tt> INSTALLED VERSIONS ------------------ commit: None python: 3.6.9 (default, Apr 18 2020, 01:56:04) [GCC 8.4.0] python-bits: 64 OS: Linux OS-release: 4.15.0-101-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 libhdf5: 1.10.4 libnetcdf: 4.6.3 xarray: 0.15.1 pandas: 1.0.3 numpy: 1.18.4 scipy: 1.4.1 netCDF4: 1.5.3 pydap: None h5netcdf: None h5py: 2.10.0 Nio: None zarr: None cftime: 1.0.4.2 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: None distributed: None matplotlib: 3.2.1 cartopy: None seaborn: 0.10.1 numbagg: None setuptools: 42.0.2 pip: 20.1.1 conda: None pytest: 4.6.2 IPython: 7.14.0 sphinx: 2.0.0 
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   completed 13221727 issue

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