Unsupported git index version 4

[mtene]

Dulwich fails to operate on git clones created by git 2.27.
The assertion that the index version should be 1,2,3 (index.py) fails, discovering version 4.
Are there plans to support this new format?
https://git-scm.com/docs/index-format

As a workaround, one can ask git to downgrade the index version:
git update-index --index-version 3
which makes dulwich succeed

[jelmer]

This format doesn't appear to be used by default as far as I can tell (on git 2.37 here). Perhaps in specific circumstances only?

I don't have concrete plans to work on support for it myself (there's a long backlog of higher priority items), but happy to review PRs that add support. This should be fairly straightforward to do by patching dulwich.index.read_cache_entry to understand the new prefixed path format.