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.

{
        setKeyPool.insert(nIndex);
        
        
        
        CKeyID keyid = keypool.vchPubKey.GetID();
        if (mapKeyMetadata.count(keyid) == 0)
            mapKeyMetadata[keyid] = CKeyMetadata(keypool.nTime);
    }
    std::map<CKeyID, CKeyMetadata> mapKeyMetadata;
    typedef std::map<unsigned int, CMasterKey> MasterKeyMap;
    MasterKeyMap mapMasterKeys;
    unsigned int nMasterKeyMaxID;
    CWallet()
    {
        SetNull();
    }
    CWallet(const std::string& strWalletFileIn) : strWalletFile(strWalletFileIn)
    {
        SetNull();
        fFileBacked = true;
    }
    ~CWallet()
    {
        delete pwalletdbEncryption;
        pwalletdbEncryption = NULL;
    }
    void SetNull()