issues: 521317260

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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
521317260 MDU6SXNzdWU1MjEzMTcyNjA= 3512 selection from MultiIndex does not work properly 6815844 closed 0     0 2019-11-12T04:12:12Z 2019-11-14T11:56:18Z 2019-11-14T11:56:18Z MEMBER      

MCVE Code Sample

```python da = xr.DataArray([0, 1], dims=['x'], coords={'x': [0, 1], 'y': 'a'}) db = xr.DataArray([2, 3], dims=['x'], coords={'x': [0, 1], 'y': 'b'}) data = xr.concat([da, db], dim='x').set_index(xy=['x', 'y']) data.sel(y='a')

<xarray.DataArray (x: 4)> array([0, 1, 2, 3]) Coordinates: * x (x) int64 0 1 ```

Expected Output

```python

<xarray.DataArray (x: 2)> array([0, 1]) Coordinates: * x (x) int64 0 1 ```

Problem Description

Should select the array

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.8 |Anaconda, Inc.| (default, Dec 30 2018, 01:22:34) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: 3.10.0-957.10.1.el7.x86_64 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: 4.6.1 xarray: 0.14.0 pandas: 0.24.2 numpy: 1.15.4 scipy: 1.2.1 netCDF4: 1.4.2 pydap: None h5netcdf: None h5py: 2.9.0 Nio: None zarr: None cftime: 1.0.3.4 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: 1.2.1 dask: None distributed: None matplotlib: 3.0.2 cartopy: None seaborn: 0.9.0 numbagg: None setuptools: 40.8.0 pip: 19.0.3 conda: None pytest: 5.0.0 IPython: 7.3.0 sphinx: None

Sorry for being quiet for a long time. I hope I could send a fix for this in a few days...

 
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   completed 13221727 issue

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