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.
{
    CAmount nTotal = 0;
    {
        LOCK2(cs_main, cs_wallet);
        for (std::map<uint256, CWalletTx>::const_iterator it = mapWallet.begin(); it != mapWallet.end(); ++it)
        {
            const CWalletTx* pcoin = &(*it).second;
            nTotal += pcoin->GetImmatureWatchOnlyCredit();
        }
    }
    return nTotal;
}
CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth, const std::string* account) const
{
    LOCK2(cs_main, cs_wallet);
    CAmount balance = 0;
    for (const auto& entry : mapWallet) {
        const CWalletTx& wtx = entry.second;
        const int depth = wtx.GetDepthInMainChain();
        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.GetBlocksToMaturity() > 0) {
            continue;
        }
        
        
        CAmount debit = wtx.GetDebit(filter);
        const bool outgoing = debit > 0;
        for (const CTxOut& out : wtx.tx->vout) {