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);
        
        map<uint256, CWalletTx>::const_iterator mi = mapWallet.find(hashTx);
        if (mi != mapWallet.end())
            NotifyTransactionChanged(this, hashTx, CT_UPDATED);
    }
}
void CWallet::GetScriptForMining(boost::shared_ptr<CReserveScript> &script)
{
    boost::shared_ptr<CReserveKey> rKey(new CReserveKey(this));
    CPubKey pubkey;
    if (!rKey->GetReservedKey(pubkey))
        return;
    script = rKey;
    script->reserveScript = CScript() << ToByteVector(pubkey) << OP_CHECKSIG;
}
void CWallet::LockCoin(const COutPoint& output)
{
    AssertLockHeld(cs_wallet); 
    setLockedCoins.insert(output);
}
void CWallet::UnlockCoin(const COutPoint& output)