Summary

libvcs's pytest plugin defines a session-scoped gitconfig fixture that returns a pathlib.Path. The third-party plugin pytest-gitconfig defines a fixture with the same name that returns a GitConfig helper object with a .set() method. When both plugins are installed and auto-loaded, libvcs wins fixture resolution and any downstream test that calls gitconfig.set(...) crashes:

AttributeError: 'PosixPath' object has no attribute 'set'

This was reported downstream against the Arch python-copier package, where the build runs upstream copier's tests with python -m venv --system-site-packages, exposing the system-installed python-libvcs plugin to the test environment: https://aur.archlinux.org/packages/python-copier#comment-1070264

Where the collision lives

• libvcs registers as the pytest plugin name libvcs via [project.entry-points.pytest11] in pyproject.toml.
• The colliding fixture is gitconfig in src/libvcs/pytest_plugin.py — session-scoped, returns pathlib.Path.
• A sibling hgconfig fixture has the same shape and would collide with any equivalent third-party plugin.

The other fixtures in this module already use a vcs_ prefix (vcs_name, vcs_email, vcs_user); gitconfig / hgconfig are the outliers in that module's own naming convention.

Reproduction

$ pip install libvcs pytest-gitconfig
$ cat > test_collision.py <<'PYEOF'
def test_gitconfig_has_set(gitconfig):
    gitconfig.set({"user.name": "x"})
PYEOF
$ pytest test_collision.py
# AttributeError: 'PosixPath' object has no attribute 'set'
$ pytest -p no:libvcs test_collision.py
# passes — pytest-gitconfig's fixture is now visible

Suggested fix

Rename libvcs's gitconfig and hgconfig fixtures to vacate the shared namespace — for example, vcs_gitconfig / vcs_hgconfig, matching the existing vcs_* convention. Internal references (set_gitconfig, git_repo, git_remote_repo, etc.) would be updated at the same time.

If keeping the short names is preferred, a deprecation alias (old name → new name with a DeprecationWarning) would let downstreams migrate without immediate breakage; once the old name is gone, the namespace is free.

I'm happy to send a PR if the rename direction is acceptable.

Workaround for downstream packagers

Until libvcs ships a fix, packagers whose test environment leaks libvcs in (e.g. python -m venv --system-site-packages) can disable just this plugin:

$ pytest -p no:libvcs ...