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.

SetAddressBook(account.vchPubKey.GetID(), strAccount, "receive");
        walletdb.WriteAccount(strAccount, account);
    }
    pubKey = account.vchPubKey;
    return true;
}
void CWallet::MarkDirty()
{
    {
        LOCK(cs_wallet);
        BOOST_FOREACH(PAIRTYPE(const uint256, CWalletTx)& item, mapWallet)
            item.second.MarkDirty();
    }
}
bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFlushOnClose)
{
    LOCK(cs_wallet);
    CWalletDB walletdb(strWalletFile, "r+", fFlushOnClose);
    uint256 hash = wtxIn.GetHash();
    
    pair<map<uint256, CWalletTx>::iterator, bool> ret = mapWallet.insert(make_pair(hash, wtxIn));
    CWalletTx& wtx = (*ret.first).second;
    wtx.BindWallet(this);
    bool fInsertedNew = ret.second;
    if (fInsertedNew)
    {
        wtx.nTimeReceived = GetAdjustedTime();
        wtx.nOrderPos = IncOrderPosNext(&walletdb);
        wtxOrdered.insert(make_pair(wtx.nOrderPos, TxPair(&wtx, (CAccountingEntry*)0)));
        wtx.nTimeSmart = wtx.nTimeReceived;