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
309686915,MDU6SXNzdWUzMDk2ODY5MTU=,2027,square-bracket slice a Dataset with a DataArray,6213168,open,0,,,4,2018-03-29T09:39:57Z,2022-04-18T03:51:25Z,,MEMBER,,,,"Given this:
```
ds = xarray.Dataset(
    data_vars={
        'vote': ('pupil', [5, 7, 8]),
        'age': ('pupil', [15, 14, 16])
    },
    coords={
        'pupil': ['Alice', 'Bob', 'Charlie']
    })


<xarray.Dataset>
Dimensions:  (pupil: 3)
Coordinates:
  * pupil    (pupil) <U7 'Alice' 'Bob' 'Charlie'
Data variables:
    vote     (pupil) int64 5 7 8
    age      (pupil) int64 15 14 16
```

Why does this work:
```
ds.age[ds.vote >= 6]

<xarray.DataArray 'age' (pupil: 2)>
array([14, 16])
Coordinates:
  * pupil    (pupil) <U7 'Bob' 'Charlie'
```

But this doesn't?
```
ds[ds.vote >= 6]

KeyError: False
```
``ds.vote >= 6`` is a DataArray with dims=('pupil', ) and dtype=bool, so I can't think of any ambiguity in what I want to achieve?

Workaround:
```
ds.sel(pupil=ds.vote >= 6)


<xarray.Dataset>
Dimensions:  (pupil: 2)
Coordinates:
  * pupil    (pupil) <U7 'Bob' 'Charlie'
Data variables:
    vote     (pupil) int64 7 8
    age      (pupil) int64 14 16
```","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/2027/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue