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.
continue;
            }
        }
        if (nChangePosInOut == -1) reservekey.ReturnKey(); 
        if (sign)
        {
            CTransaction txNewConst(txNew);
            int nIn = 0;
            for (const auto& coin : setCoins)
            {
                const CScript& scriptPubKey = coin.txout.scriptPubKey;
                SignatureData sigdata;
                if (!ProduceSignature(TransactionSignatureCreator(this, &txNewConst, nIn, coin.txout.nValue, SIGHASH_ALL), scriptPubKey, sigdata))
                {
                    strFailReason = _("Signing transaction failed");
                    return false;
                } else {
                    UpdateTransaction(txNew, nIn, sigdata);
                }
                nIn++;
            }
        }
        
        wtxNew.SetTx(MakeTransactionRef(std::move(txNew)));
        
        if (GetTransactionWeight(wtxNew) >= MAX_STANDARD_TX_WEIGHT)
        {
            strFailReason = _("Transaction too large");
            return false;
        }