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/pull/4392#issuecomment-687844137,https://api.github.com/repos/pydata/xarray/issues/4392,687844137,MDEyOklzc3VlQ29tbWVudDY4Nzg0NDEzNw==,5821660,2020-09-06T17:09:00Z,2020-09-06T17:09:00Z,MEMBER,"I think my latest changes according to @dcherian's comments are now backwards compatible. Short explanation:

- `allow_rechunk` is None (default)
    - if core dimension chunks > 1 raise ValueError (to keep backward compatibility concerning core dimension chunking)
    - else sets `allow_rechunk=True` (to keep backward compatibility concerning chunking mismatch in non-core dimensions
- `allow_rechunk` == True  (user need to explicitoly set this in the `dask_gufunc_kwargs`)
    - just call `apply_gufunc`
- `allow_rechunk` == False (user need to explicitoly set this in the `dask_gufunc_kwargs`)
    - just call `apply_gufunc`


","{""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,688993462
https://github.com/pydata/xarray/pull/4392#issuecomment-686966421,https://api.github.com/repos/pydata/xarray/issues/4392,686966421,MDEyOklzc3VlQ29tbWVudDY4Njk2NjQyMQ==,5821660,2020-09-04T07:23:06Z,2020-09-04T07:23:06Z,MEMBER,"@dcherian I think, that this is almost good to go. Any rework on the warning message needed?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,688993462
https://github.com/pydata/xarray/pull/4392#issuecomment-683634677,https://api.github.com/repos/pydata/xarray/issues/4392,683634677,MDEyOklzc3VlQ29tbWVudDY4MzYzNDY3Nw==,5821660,2020-08-31T08:11:52Z,2020-08-31T08:12:25Z,MEMBER,"As laid out in #4372 the behaviour before #4060 was to run `blockwise` with automatically aligning non-core dimensions (permit rechunking). For multiple chunks in core dimensions a ValueError would have been thrown. 

If I understand the comments of @dcherian and @shoyer in #4372 correctly, `allow_rechunk` should be set `True` in the first case but not in the second. 

This PR just checks for the dask ValueError which is raised for non-core dimension chunk mismatch, issues a warning, that the behaviour will change in the future (not sure if this is intended, please recommend otherwise) and reruns `apply_gufunc` with `allow_rechunk=True`. For the second case the dask ValueError is raised. 
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,688993462