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
282916278,MDU6SXNzdWUyODI5MTYyNzg=,1789,Broken link to github on ReadTheDocs ,25473287,closed,0,,,8,2017-12-18T15:24:04Z,2018-10-25T16:24:27Z,2018-10-25T16:24:27Z,NONE,,,,"The ""Edit on GitHub"" button on [ReadTheDocs](http://xarray.pydata.org/en/stable/) is linked to
https://github.com/pydata/xarray/blob/origin/stable/doc/index.rst
which doesn't exist. The correct URL would be without ""origin"":
https://github.com/pydata/xarray/blob/stable/doc/index.rst","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/1789/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed,13221727,issue
298834332,MDU6SXNzdWUyOTg4MzQzMzI=,1931,apply_ufunc produces illegal coordinate sizes,25473287,closed,0,,,5,2018-02-21T03:58:19Z,2018-05-31T15:40:04Z,2018-05-31T15:40:04Z,NONE,,,,"If `func` changes the size of the core dimension, `apply_ufunc(func, ..)` will only change the data variable dimension but keep the coordinate dimension and value unchanged. The resulting DataArray cannot be saved to a NetCDF file due to dimension inconsistency. Please see this [GitHub gist](https://gist.github.com/JiaweiZhuang/89a6bce7d5adc473134c7014bec065a0) for a simple illustration. 

Would it be more natural to drop the core coordinate by default? This is safer (will not produce illegal NetCDF file) and also makes more physical sense (the core coordinate is likely to change).

I'd like use `apply_ufunc` to track metadata in my xESMF package, but the output DataArray will have incorrect `lon` and `lat` coordinate dimension and values. It is easy to manually correct this afterwards but I want to bring up this issue.

#### Output of ``xr.show_versions()``
<details>

commit: None
python: 3.6.2.final.0
python-bits: 64
OS: Darwin
OS-release: 16.7.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

xarray: 0.10.0
pandas: 0.22.0
numpy: 1.13.3
scipy: 1.0.0
netCDF4: 1.3.1
h5netcdf: 0.5.0
Nio: None
bottleneck: 1.2.1
cyordereddict: None
dask: 0.17.0
matplotlib: 2.0.2
cartopy: 0.15.1
seaborn: 0.8.0
setuptools: 38.2.5
pip: 9.0.1
conda: None
pytest: 3.2.5
IPython: 6.1.0
sphinx: 1.6.5
</details>
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