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.

{
        nChange += GetChange(txout);
        if (!MoneyRange(nChange))
            throw std::runtime_error(std::string(__func__) + ": value out of range");
    }
    return nChange;
}
CPubKey CWallet::GenerateNewHDMasterKey()
{
    CKey key;
    key.MakeNewKey(true);
    int64_t nCreationTime = GetTime();
    CKeyMetadata metadata(nCreationTime);
    
    CPubKey pubkey = key.GetPubKey();
    assert(key.VerifyPubKey(pubkey));
    
    metadata.hdKeypath     = "m";
    metadata.hdMasterKeyID = pubkey.GetID();
    {
        LOCK(cs_wallet);
        
        mapKeyMetadata[pubkey.GetID()] = metadata;
        
        if (!AddKeyPubKey(key, pubkey))
            throw std::runtime_error(std::string(__func__) + ": AddKeyPubKey failed");
    }
    return pubkey;
}
bool CWallet::SetHDMasterKey(const CPubKey& pubkey)