Method fix_submodule_gitdir_path

src/git.rs:787–838

Fix the gitdir path in a submodule .git file if it uses an absolute path.

(
        &self,
        git_file: &Path,
        repo_path: &Path,
    )

    /// Fix the gitdir path in a submodule .git file if it uses an absolute path.
    async fn fix_submodule_gitdir_path(
        &self,
        git_file: &Path,
        repo_path: &Path,
    ) -> Result<(), String> {
        let content = tokio::fs::read_to_string(git_file)
            .await
            .map_err(|e| format!("Failed to read {}: {}", git_file.display(), e))?;

        let gitdir_line = content.trim();
        if !gitdir_line.starts_with("gitdir: ") {
            return Err(format!("Invalid .git file format: {}", git_file.display()));
        }

        let gitdir_path = gitdir_line.strip_prefix("gitdir: ").unwrap_or("").trim();

        // Check if it's an absolute path (starts with / or contains : for Windows)
        if gitdir_path.starts_with('/') || gitdir_path.contains(':') {
            // Absolute path needs rewriting
            // Extract the module path from the absolute path
            if let Some(modules_pos) = gitdir_path.find("/.git/modules/") {
                let module_path = &gitdir_path[modules_pos + "/.git/modules/".len()..];
                let submodule_dir = git_file
                    .parent()
                    .ok_or_else(|| "No parent directory".to_string())?;
                let depth = submodule_dir
                    .strip_prefix(repo_path)
                    .map_err(|_| "Path not under repo".to_string())?
                    .components()
                    .count();

                let prefix = if depth > 0 {
                    "../".repeat(depth)
                } else {
                    "./".to_string()
                };
                let new_gitdir = format!("{}.git/modules/{}", prefix, module_path);

                tokio::fs::write(git_file, format!("gitdir: {}\n", new_gitdir))
                    .await
                    .map_err(|e| format!("Failed to write {}: {}", git_file.display(), e))?;
            } else {
                return Err(format!(
                    "Could not extract module path from absolute gitdir: {}",
                    gitdir_path
                ));
            }
        }
        // Relative paths should work as-is since the structure is preserved

        Ok(())
    }

    /// Fix worktree paths in .git/modules/*/config files if they use absolute paths.
    /// Returns any warnings encountered during the fix.