async fn repo_presence(cwd: &Path) -> RepoPresenceExpand description
Ask whether cwd sits inside a git repo with rev-parse --git-dir,
whose exit status answers repo-existence alone: zero inside any work
tree including one with no commits, non-zero outside one and for a
path that does not exist. Matching git’s fatal: prose would not
work here even setting version drift aside - a deleted .git/HEAD
and a plain non-repo emit the same line.
A non-zero exit is then refined by whether .git is on disk: a
pruned worktree entry, a deleted HEAD and a corrupt gitfile all
exit 128 with .git still present, and each is a fault to report
rather than an absent repo. Undeterminable biases to Unusable, so
a broken checkout is never silently suppressed.
Not routed through run_git: a non-zero exit is the answer here
rather than a fault, so it must neither be logged as a failure nor
collapsed with “git would not run”, which the caller has already
logged with git’s stderr.