if limit < 0 || len(merged) < limit {
		merged = append(merged, a...)
		merged = append(merged, b...)
	}
	m.o = merged
}

// filterPrefix will filter m to only contain entries with the specified prefix.
func (m *metaCacheEntriesSorted) filterPrefix(s string) {
	if s == "" {
		return
	}
	m.forwardTo(s)
	for i, o := range m.o {
		if !o.hasPrefix(s) {
			m.o = m.o[:i]
			break
		}
	}