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.
{
    LOCK2(cs_main, cs_wallet);
    fFirstRunRet = false;
    DBErrors nLoadWalletRet = CWalletDB(*dbw,"cr+").LoadWallet(this);
    if (nLoadWalletRet == DB_NEED_REWRITE)
    {
        if (dbw->Rewrite("\x04pool"))
        {
            setInternalKeyPool.clear();
            setExternalKeyPool.clear();
            m_pool_key_to_index.clear();
            
            
            
        }
    }
    
    fFirstRunRet = mapKeys.empty() && mapCryptedKeys.empty() && mapWatchKeys.empty() && setWatchOnly.empty() && mapScripts.empty();
    if (nLoadWalletRet != DB_LOAD_OK)
        return nLoadWalletRet;
    uiInterface.LoadWallet(this);
    return DB_LOAD_OK;
}
DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut)