Do not raise if branch exists and no write permission

[Wauplin]

Fix #2419 (and huggingface/datasets#7067 / huggingface/datasets#7069).

When creating a repo with exists_ok=True, if the user do not have permission to create it but the repo already exists, an HTTP 403 is returned by the server. We catch this error client-side and ignore it since the repo exists. This PR adds the same logic for create_branch.

cc @albertvillanova @lhoestq

[HuggingFaceDocBuilderDev]

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[albertvillanova]

Thanks for the fix, @Wauplin.

Just to comment on another similar situation (reported as well by the community: https://discuss.huggingface.co/t/convert-to-parquet-fails-for-datasets-with-multiple-configs/86733/4).

When the user passes an existing PR branch, e.g. "refs/pr/1", and exists_ok=True:

• In this case, a 400 Bad Request error is raised.
• Should we raise or not in this case?

[Wauplin]

Thanks for the reviews!

When the user passes an existing PR branch, e.g. "refs/pr/1", and exists_ok=True:

I think this should be something to fix in datasets directly. Having a 400 Bad request when trying to create the branch refs/pr/1 seems normal to me since it's not a branch.