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.

{
                if (nOrderPos >= nOffsetStart)
                    ++nOrderPosOff;
            }
            nOrderPos += nOrderPosOff;
            nOrderPosNext = std::max(nOrderPosNext, nOrderPos + 1);
            if (!nOrderPosOff)
                continue;
            
            if (pwtx)
            {
                if (!walletdb.WriteTx(*pwtx))
                    return DB_LOAD_FAIL;
            }
            else
                if (!walletdb.WriteAccountingEntry(pacentry->nEntryNo, *pacentry))
                    return DB_LOAD_FAIL;
        }
    }
    walletdb.WriteOrderPosNext(nOrderPosNext);
    return DB_LOAD_OK;
}
int64_t CWallet::IncOrderPosNext(CWalletDB *pwalletdb)