This is the exact same steps followed in #8656

But hopefully with a clean history.

I am copying the notes from the previous PR below.

https://github.com/flamingbear/rewritten-datatree is the version of datatree that was m erged in this PR.

---

Previous PR notes This PR imports xarray-contrib/datatree and its history to pydata/xarray/xarray/datatree_

Step one of issue #8572. This imports the datatree code without exposing DataTree as a public API.

git filter repo https://github.com/newren/git-filter-repo was used to preserve some history for the merge.

Datatree tags were renamed to legacy-datatree-{tag}:

shell git filter-repo --tag-rename '':'legacy-datatree-'

Links to xarray-contrib/datatree original PRs are preserved by rewriting the messages using a replace-message file.

``` text

standard github style pull request (#39)

regex:(#(\d+))==>https://github.com/xarray-contrib/datatree/pull/\1

"Merge pull request #11 from TomNicholas/single_datanode_class"

regex:pull request #(\d+)==>https://github.com/xarray-contrib/datatree/pull/\1 ```

Links to the xarray-contrib/datatree Issues are preserved with a replace-text file.

``` text

standard comment change " # see issue #38"

regex:(\s?#.[ ])#(\d+)==>\1https://github.com/xarray-contrib/datatree/issues/\2

also " @pytest.mark.xfail(reason="Indexing needs to return whole tree (GH #77)")"

regex:((GH #(\d+)))==>(GH https://github.com/xarray-contrib/datatree/issues/\2) ```

The datatree repo was relocated to a subdirectory

shell git-filter-repo --to-subdirectory xarray/datatree_

and the prepared datatree repository was added as a remote and merged into xarray.

shell git merge prepared-datatree/main --no-commit --allow-unrelated-histories

This should allow work to begin on the rest of the steps in #8572