html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/2551#issuecomment-437707951,https://api.github.com/repos/pydata/xarray/issues/2551,437707951,MDEyOklzc3VlQ29tbWVudDQzNzcwNzk1MQ==,10050469,2018-11-11T21:46:02Z,2018-11-11T21:46:02Z,MEMBER,">  but now operates lazily.

If so, how does the dataset access the data if the file is closed? Shouldn't it raise an error instead?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,379177627
https://github.com/pydata/xarray/issues/2551#issuecomment-437705060,https://api.github.com/repos/pydata/xarray/issues/2551,437705060,MDEyOklzc3VlQ29tbWVudDQzNzcwNTA2MA==,10050469,2018-11-11T21:08:13Z,2018-11-11T21:08:13Z,MEMBER,Actually I have to ask: why is it possible to to an operation on a closed dataset? What is happening under the hood which creates this error and wasn't earlier?,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,379177627
https://github.com/pydata/xarray/issues/2551#issuecomment-437664983,https://api.github.com/repos/pydata/xarray/issues/2551,437664983,MDEyOklzc3VlQ29tbWVudDQzNzY2NDk4Mw==,10050469,2018-11-11T12:10:36Z,2018-11-11T12:10:36Z,MEMBER,"> Yep, that looks a bug on your end. Were you using autoclose=True before?

No, the exact same piece of code works without error with xarray prev 0.11. Closing this now!","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,379177627
https://github.com/pydata/xarray/issues/2551#issuecomment-437574599,https://api.github.com/repos/pydata/xarray/issues/2551,437574599,MDEyOklzc3VlQ29tbWVudDQzNzU3NDU5OQ==,10050469,2018-11-10T10:39:09Z,2018-11-10T10:40:35Z,MEMBER,"> I am slightly regretting not doing a release candidate here,

I should be better placed than anyone to anticipate and test more frequently on master :roll_eyes: 

So this reproduces the problem on my machine and [travis](https://travis-ci.org/pydata/xarray/builds/453229051?utm_source=github_status&utm_medium=notification). Note the misplaced computation out of the `with` block:

```python
import xarray as xr
import numpy as np
import netCDF4
import os

try:
    os.remove('test.nc')
except OSError:
    pass

thick = np.zeros((180, 200), np.float32)

ds = xr.Dataset()
ds['thick'] = (('y', 'x'), thick)
ds.to_netcdf('test.nc')

with xr.open_dataset('test.nc') as ds:
    dummy = ds.thick.isel(x=('z', [1, 3, 4]), y=('z', [7, 2, 1]))
    
dummy.min()  # this is the issue

with netCDF4.Dataset('test.nc', 'a') as nc:
    nc.variables['thick'][:] = thick  
```

I guess this was actually a bug in our code, but for some reason it worked fine with earlier xarray versions. I'm not sure if this requires action on the xarray side in the end...","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,379177627