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.

{
    LOCK(cs_wallet);
    CWalletDB walletdb(strWalletFile);
    
    
    
    typedef pair<CWalletTx*, CAccountingEntry*> TxPair;
    typedef multimap<int64_t, TxPair > TxItems;
    TxItems txByTime;
    for (map<uint256, CWalletTx>::iterator it = mapWallet.begin(); it != mapWallet.end(); ++it)
    {
        CWalletTx* wtx = &((*it).second);
        txByTime.insert(make_pair(wtx->nTimeReceived, TxPair(wtx, (CAccountingEntry*)0)));
    }
    list<CAccountingEntry> acentries;
    walletdb.ListAccountCreditDebit("", acentries);
    BOOST_FOREACH(CAccountingEntry& entry, acentries)