When a pass of CreateTransaction fails to select enough bitcoin to meet the nFeeNeeded the next pass through may select a far smaller collection of inputs.  Currently it will continue to use the old fee amount based on the larger set of inputs, which can cause a non-trivial over-payment.

This may be the cause of the behavior reported here: https://www.reddit.com/r/Bitcoin/comments/5ltw5n/bitcoin_core_v0131_sends_enormously_high_fee/

Long ago fixing this was tricky due to a catch-22 between signing the transaction and knowing how much fee was required.  But after #9465 the whole algorithm will run using a dummy signature, so when there is already a change output fixing up the fee after finding a sufficient transaction should be a matter of a ~2 line change.

bool LoadWatchOnly(const CScript &dest);
    bool Unlock(const SecureString& strWalletPassphrase);
    bool ChangeWalletPassphrase(const SecureString& strOldWalletPassphrase, const SecureString& strNewWalletPassphrase);
    bool EncryptWallet(const SecureString& strWalletPassphrase);
    void GetKeyBirthTimes(std::map<CKeyID, int64_t> &mapKeyBirth) const;
    /** 
     * Increment the next transaction order id
     * @return next transaction order id
     */
    int64_t IncOrderPosNext(CWalletDB *pwalletdb = NULL);
    DBErrors ReorderTransactions();
    bool AccountMove(std::string strFrom, std::string strTo, CAmount nAmount, std::string strComment = "");
    bool GetAccountPubkey(CPubKey &pubKey, std::string strAccount, bool bForceNew = false);
    void MarkDirty();
    bool AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose=true);
    bool LoadToWallet(const CWalletTx& wtxIn);
    void SyncTransaction(const CTransaction& tx, const CBlockIndex *pindex, int posInBlock);
    bool AddToWalletIfInvolvingMe(const CTransaction& tx, const CBlockIndex* pIndex, int posInBlock, bool fUpdate);
    int ScanForWalletTransactions(CBlockIndex* pindexStart, bool fUpdate = false);
    void ReacceptWalletTransactions();
    void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman);
    std::vector<uint256> ResendWalletTransactionsBefore(int64_t nTime, CConnman* connman);
    CAmount GetBalance() const;
    CAmount GetUnconfirmedBalance() const;
    CAmount GetImmatureBalance() const;
    CAmount GetWatchOnlyBalance() const;
    CAmount GetUnconfirmedWatchOnlyBalance() const;
    CAmount GetImmatureWatchOnlyBalance() const;
    /**