Function local_base 

async fn local_base(
    cwd: &Path,
    default_branch: &str,
    deadline: Option<Instant>,
) -> (BaseState, Option<String>)

The state of a base that names no remote-tracking ref, and the sha it resolves to: the probes a local base owes.

A local base has no ref to fetch. With an origin remote it can still be arbitrarily behind one nobody ever fetched, and there is no remote-tracking ref to name that lag against, so the base is not claimed rather than silently called local. A base that tracks a remote of its own can lag too: a local main whose upstream is upstream/main is stale exactly as an origin/main would be, and calling it local would be the same silence.