fix: let GIT_WORK_TREE override core.bare

[Daniel Castrillon (danielcadev)]

Description

Honor the GIT_WORK_TREE environment override when opening a repository configured with core.bare=true.

Git treats an explicit GIT_WORK_TREE as an effective worktree and reports the repository as non-bare. gix previously retained workdir: None, which prevented downstream consumers such as Starship from computing repository status.

The override is deliberately limited to GIT_WORK_TREE. A core.worktree CLI override still does not supersede core.bare, matching Git behavior.

Related downstream issue: starship/starship#7609
Supersedes the downstream workaround proposed in starship/starship#7617.

#1985 and #1987 addressed the strict-config error associated with GIT_WORK_TREE, but did not cover its interaction with core.bare.

Tests

• Added a regression test for a bare repository with an external GIT_WORK_TREE.
• Confirmed the repository becomes non-bare and status observes files in the external worktree.
• Added a negative control proving that -c core.worktree=... does not override core.bare.
• cargo fmt --all -- --check
• Strict Clippy for gix
• Complete cargo test -p gix --no-fail-fast: 410 passed

AI assistance

Codex assisted with investigation, implementation, testing, and preparation of this pull request. I reviewed the changes and verified the behavior locally against Git.

[chatgpt-codex-connector]

💡 Codex Review

gitoxide/gix/src/open/repository.rs

Line 308 in 79e7dbf

worktree_dir = gix_path::normalize(wt_path.into(), current_dir).map(Cow::into_owned);

Handle over-root worktree paths before clearing bare

When a relative GIT_WORK_TREE contains more .. components than the current directory's depth, Git and the OS resolve through the root, but gix_path::normalize() returns None here. The subsequent config.is_bare = Some(false) therefore creates a repository with workdir() == None and is_bare() == false, causing index/worktree status to fail with MissingWorkDir instead of using the explicitly requested worktree. Treat normalization failure as an error or normalize this valid environment path with filesystem semantics before marking the repository non-bare.

AGENTS.md reference: AGENTS.md:L16-L18

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[Daniel Castrillon (danielcadev)]

Oh, okay, good catch. Thanks! I reproduced it with a relative GIT_WORK_TREE that traverses beyond the filesystem root. Git saturates at the root, while my original patch left gix non-bare without a worktree.

I updated the normalization only for the GIT_WORK_TREE environment override and added a regression that verifies both the resolved worktree and status traversal. The full gix suite (410 tests), formatting, and strict Clippy pass.