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.
if (currentconfirm == 0 && !wtx.isAbandoned()) {
            
            assert(!wtx.InMempool());
            wtx.nIndex = -1;
            wtx.setAbandoned();
            wtx.MarkDirty();
            walletdb.WriteTx(wtx);
            NotifyTransactionChanged(this, wtx.GetHash(), CT_UPDATED);
            
            TxSpends::const_iterator iter = mapTxSpends.lower_bound(COutPoint(hashTx, 0));
            while (iter != mapTxSpends.end() && iter->first.hash == now) {
                if (!done.count(iter->second)) {
                    todo.insert(iter->second);
                }
                iter++;
            }
            
            
            for (const CTxIn& txin : wtx.tx->vin)
            {
                auto it = mapWallet.find(txin.prevout.hash);
                if (it != mapWallet.end()) {
                    it->second.MarkDirty();
                }
            }
        }
    }
    return true;
}
void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)