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.
bool IsAbortingRescan() { return fAbortRescan; }
    bool IsScanning() { return fScanningWallet; }
    /**
     * keystore implementation
     * Generate a new key
     */
    CPubKey GenerateNewKey(CWalletDB& walletdb, bool internal = false);
    
    bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey) override;
    bool AddKeyPubKeyWithDB(CWalletDB &walletdb,const CKey& key, const CPubKey &pubkey);
    
    bool LoadKey(const CKey& key, const CPubKey &pubkey) { return CCryptoKeyStore::AddKeyPubKey(key, pubkey); }
    
    bool LoadKeyMetadata(const CTxDestination& pubKey, const CKeyMetadata &metadata);
    bool LoadMinVersion(int nVersion) { AssertLockHeld(cs_wallet); nWalletVersion = nVersion; nWalletMaxVersion = std::max(nWalletMaxVersion, nVersion); return true; }
    void UpdateTimeFirstKey(int64_t nCreateTime);
    
    bool AddCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret) override;