// Copy all prior info, except for the root goroutine (goid 0).
	if debug.tracebackancestors <= 0 || callergp.goid == 0 {
		return nil
	}
	var callerAncestors []ancestorInfo
	if callergp.ancestors != nil {
		callerAncestors = *callergp.ancestors
	}
	n := int32(len(callerAncestors)) + 1
	if n > debug.tracebackancestors {
		n = debug.tracebackancestors
	}
	ancestors := make([]ancestorInfo, n)