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.
{
    std::shared_ptr<CReserveKey> rKey = std::make_shared<CReserveKey>(this);
    CPubKey pubkey;
    if (!rKey->GetReservedKey(pubkey))
        return;
    script = rKey;
    script->reserveScript = CScript() << ToByteVector(pubkey) << OP_CHECKSIG;
}
void CWallet::LockCoin(const COutPoint& output)
{
    AssertLockHeld(cs_wallet); 
    setLockedCoins.insert(output);
}
void CWallet::UnlockCoin(const COutPoint& output)
{
    AssertLockHeld(cs_wallet); 
    setLockedCoins.erase(output);
}
void CWallet::UnlockAllCoins()