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.
{
    {
        LOCK(cs_wallet);
        CWalletDB walletdb(*dbw);
        for (int64_t nIndex : setInternalKeyPool) {
            walletdb.ErasePool(nIndex);
        }
        setInternalKeyPool.clear();
        for (int64_t nIndex : setExternalKeyPool) {
            walletdb.ErasePool(nIndex);
        }
        setExternalKeyPool.clear();
        m_pool_key_to_index.clear();
        if (!TopUpKeyPool()) {
            return false;
        }
        LogPrintf("CWallet::NewKeyPool rewrote keypool\n");
    }
    return true;
}
size_t CWallet::KeypoolCountExternalKeys()