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/1509#issuecomment-322894661,https://api.github.com/repos/pydata/xarray/issues/1509,322894661,MDEyOklzc3VlQ29tbWVudDMyMjg5NDY2MQ==,2443309,2017-08-16T20:48:16Z,2017-08-16T20:48:16Z,MEMBER,"1) I can reproduce this behavior on the current master branch
2) this is consistent with numpy's `nansum`/`nanmean` which we use here

```python
In [1]: import numpy as np

In [2]: np.sum([np.nan])
Out[2]: nan

In [3]: np.mean([np.nan])
Out[3]: nan

In [4]: np.nansum([np.nan])
Out[4]: 0.0

In [5]: np.nanmean([np.nan])
/glade/u/home/jhamman/anaconda/envs/storylines/bin/ipython:1: RuntimeWarning: Mean of empty slice
  #!/glade/u/home/jhamman/anaconda/envs/storylines/bin/python
Out[5]: nan
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,250751931