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
1331855489,PR_kwDOAMm_X8480Dc3,6889,Harmonize returned multi-indexed indexes when applying `concat` along new dimension ,19226431,closed,0,,,6,2022-08-08T13:12:45Z,2022-08-25T14:12:55Z,2022-08-25T11:15:54Z,CONTRIBUTOR,,0,pydata/xarray/pulls/6889,"- [x] Closes #6881 
- [x] Tests added

In the current implementation, the `concat` function does not ensure that the indexes that belong to the same `MultiIndex` relate to the same `MultiIndex` object in `Dataset.indexes` when concatenating along a new dimension. This becomes a problem as soon as the returned dataset needs to be aligned (for broadcasting, reindexing etc.), see #6881 for example. As far as I understand, this bug was introduced in https://github.com/pydata/xarray/pull/5692 following the idea that the `concat` function should disentangle indexes and dimensions. 

It can be fixed by not removing the index name from the list of indexes which should be merged, see https://github.com/pydata/xarray/blob/9050a8b9efc28142b762475c7285603a87b00e83/xarray/core/concat.py#L493. All indexes contained in this list will get a new index object. Currently, this list only contains the **levels** of a multi-indexed index, not the index name itself. This is removed as it is contained in `dim_names`. Instead of removing all dimension names from this list, I suggest to only remove unlabeled dimensions from this list.","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/6889/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull
1052740367,PR_kwDOAMm_X84ufPFw,5984,preserve chunked data when creating DataArray from DataArray,19226431,closed,0,,,10,2021-11-13T18:21:10Z,2022-01-13T18:10:57Z,2022-01-13T17:02:47Z,CONTRIBUTOR,,0,pydata/xarray/pulls/5984,"<!-- Feel free to remove check-list items aren't relevant to your change -->

- [x] Closes #5983 
- [x] Tests added
- [x] Passes `pre-commit run --all-files`
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5984/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull