if xl == nil {
					// Discard current "best"
					if err := selectFrom(bestIdx); err != nil {
						return err
					}
					bestIdx = idx
					best = other
					xl = xl2
				} else {
					// Mark read, unless we added it as new "best".
					if err := selectFrom(idx); err != nil {
						return err
					}
				}
				versions = append(versions, xl2.versions)
			}

			if xl != nil && len(versions) > 0 {