This is to track the regression introduced in master, which needs fixing for 0.14. See #9240, #9371, etc.
return a->GetTx().GetHash() < b->GetTx().GetHash();
        }
    };
    typedef std::set<txiter, CompareIteratorByHash> setEntries;
    const setEntries & GetMemPoolParents(txiter entry) const;
    const setEntries & GetMemPoolChildren(txiter entry) const;
private:
    typedef std::map<txiter, setEntries, CompareIteratorByHash> cacheMap;
    struct TxLinks {
        setEntries parents;
        setEntries children;
    };
    typedef std::map<txiter, TxLinks, CompareIteratorByHash> txlinksMap;
    txlinksMap mapLinks;
    void UpdateParent(txiter entry, txiter parent, bool add);
    void UpdateChild(txiter entry, txiter child, bool add);
    std::vector<indexed_transaction_set::const_iterator> GetSortedDepthAndScore() const;
public:
    indirectmap<COutPoint, const CTransaction*> mapNextTx;
    std::map<uint256, std::pair<double, CAmount> > mapDeltas;
    /** Create a new CTxMemPool.
     */
    CTxMemPool(const CFeeRate& _minReasonableRelayFee);
    ~CTxMemPool();
    /**
     * If sanity-checking is turned on, check makes sure the pool is
     * consistent (does not contain two transactions that spend the same inputs,
     * all inputs are in the mapNextTx array). If sanity-checking is turned off,
     * check does nothing.