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.
{
    
    std::vector<CWalletTx> vWtx;
    if (gArgs.GetBoolArg("-zapwallettxes", false)) {
        uiInterface.InitMessage(_("Zapping all transactions from wallet..."));
        std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, walletFile));
        std::unique_ptr<CWallet> tempWallet(new CWallet(std::move(dbw)));
        DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
        if (nZapWalletRet != DB_LOAD_OK) {
            InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
            return nullptr;
        }
    }
    uiInterface.InitMessage(_("Loading wallet..."));
    int64_t nStart = GetTimeMillis();
    bool fFirstRun = true;
    std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, walletFile));
    CWallet *walletInstance = new CWallet(std::move(dbw));
    DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
    if (nLoadWalletRet != DB_LOAD_OK)
    {
        if (nLoadWalletRet == DB_CORRUPT) {
            InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));