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.

return false;
                        }
                        scriptChange = GetScriptForDestination(vchPubKey.GetID());
                    }
                    CTxOut newTxOut(nChange, scriptChange);
                    
                    
                    
                    if (nSubtractFeeFromAmount > 0 && newTxOut.IsDust(::minRelayTxFee))
                    {
                        CAmount nDust = newTxOut.GetDustThreshold(::minRelayTxFee) - newTxOut.nValue;
                        newTxOut.nValue += nDust; 
                        for (unsigned int i = 0; i < vecSend.size(); i++) 
                        {
                            if (vecSend[i].fSubtractFeeFromAmount)
                            {
                                txNew.vout[i].nValue -= nDust;
                                if (txNew.vout[i].IsDust(::minRelayTxFee))
                                {
                                    strFailReason = _("The transaction amount is too small to send after the fee has been deducted");
                                    return false;
                                }
                                break;
                            }
                        }
                    }
                    
                    
                    if (newTxOut.IsDust(::minRelayTxFee))
                    {