Built against `master` branch 801dd40666d1e6009920ad3ff755c7bb993b2a62:

If I have no wallet.dat file and run:

    bitcoind -usehd=0

A new wallet.dat file is created and an HD seed is assigned.

I see an error message in the source:

    "Error loading %s: You can't disable HD on an already existing HD wallet or create new non-HD wallets."

but that doesn't get shown because `fFirstRun` is true, and so the code which checks for `-usehd` values doesn't run.

If it's no longer possible to create non-HD wallets, specifying -usehd=0 when creating a wallet should be an error, and not get silently ignored.
CReserveKey reservekey(this);
    CWalletTx wtx;
    if (!CreateTransaction(vecSend, wtx, reservekey, nFeeRet, nChangePosInOut, strFailReason, coinControl, false)) {
        return false;
    }
    if (nChangePosInOut != -1) {
        tx.vout.insert(tx.vout.begin() + nChangePosInOut, wtx.tx->vout[nChangePosInOut]);
        
        
        reservekey.KeepKey();
    }
    
    for (unsigned int idx = 0; idx < tx.vout.size(); idx++)
        tx.vout[idx].nValue = wtx.tx->vout[idx].nValue;
    
    for (const CTxIn& txin : wtx.tx->vin)
    {
        if (!coinControl.IsSelected(txin.prevout))
        {
            tx.vin.push_back(txin);
            if (lockUnspents)
            {
              LOCK2(cs_main, cs_wallet);
              LockCoin(txin.prevout);
            }
        }
    }
    return true;
}
bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet,