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.

CAmount& nSent, CAmount& nFee, const isminefilter& filter) const
{
    nReceived = nSent = nFee = 0;
    CAmount allFee;
    string strSentAccount;
    list<COutputEntry> listReceived;
    list<COutputEntry> listSent;
    GetAmounts(listReceived, listSent, allFee, strSentAccount, filter);
    if (strAccount == strSentAccount)
    {
        BOOST_FOREACH(const COutputEntry& s, listSent)
            nSent += s.amount;
        nFee = allFee;
    }
    {
        LOCK(pwallet->cs_wallet);
        BOOST_FOREACH(const COutputEntry& r, listReceived)