Staged area modified after cross branch checkout

I created two branches with commits like this:

Then I call checkout to switch the branch from old_master to master. Somehow, the cached area is updated after checkout:

Here's the code toe reproduce

import pathlib

import pygit2


def test_checkout(tmp_path: pathlib.Path):
    repo_dir = tmp_path

    git_author = pygit2.Signature(name="foo", email="foo@bar.com")
    repo = pygit2.init_repository(str(repo_dir))
    workdir = pathlib.Path(repo.workdir)
    readme = workdir / "README.md"

    readme.write_text("commit0")
    index = repo.index
    index.add(readme.relative_to(workdir).as_posix())
    index.write()
    tree = index.write_tree()
    commit0 = repo.create_commit("HEAD", git_author, git_author, "commit0", tree, [])

    master_branch = repo.branches.local["master"]
    old_master_branch = repo.branches.local.create("old_master", master_branch.peel())

    readme.write_text("commit1")
    index = repo.index
    index.add(readme.relative_to(workdir).as_posix())
    index.write()
    tree = index.write_tree()
    repo.create_commit(repo.head.name, git_author, git_author, "commit1", tree, [commit0])

    repo.checkout(old_master_branch)
    readme.write_text("commit2")
    index = repo.index
    index.add(readme.relative_to(workdir).as_posix())
    index.write()
    tree = index.write_tree()
    repo.create_commit(repo.head.name, git_author, git_author, "commit2", tree, [commit0])

    repo.checkout(master_branch)
    # the staged area should be empty after checkout
    assert not list(repo.index)

I tried it with git checkout master and it works fine without changing the staged area.

Commencez par exécuter le reproducer test_checkout fourni et examinez le comportement de repo.checkout et repo.index lors des deux changements de branche. Comparez l’index staged après le retour sur master avec l’état vide attendu, et vérifiez le résultat par rapport au comportement décrit de git checkout.