Method commitParents

internal/diff/git.go:509–519

commitParents returns the parent commit SHAs of ref: zero for a root commit, one for an ordinary commit, and 2+ for a merge. It uses `rev-list --parents -n 1`, whose single line is " …" — the leading commit token is dropped, the rest are the parents. `rev-list` (unlike `re

(ctx context.Context, ref string)

// looks like an option. An error yields nil so the caller treats it as "no
// unique base".
func (p *Provider) commitParents(ctx context.Context, ref string) []string {
	out, err := p.runGit(ctx, "rev-list", "--parents", "-n", "1", "--end-of-options", ref)
	if err != nil {
		return nil
	}
	fields := strings.Fields(firstLine(out))
	if len(fields) <= 1 {
		return nil // root commit (only the commit itself, no parents) or empty
	}
	return fields[1:]
}

// firstLine returns the first non-empty trimmed line of git output, so a stray
// trailing newline or an unexpected second line never pollutes a resolved SHA.