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.
copyTo->nTimeSmart = copyFrom->nTimeSmart;
                    copyTo->fFromMe = copyFrom->fFromMe;
                    copyTo->strFromAccount = copyFrom->strFromAccount;
                    copyTo->nOrderPos = copyFrom->nOrderPos;
                    walletdb.WriteTx(*copyTo);
                }
            }
        }
    }
    walletInstance->SetBroadcastTransactions(gArgs.GetBoolArg("-walletbroadcast", DEFAULT_WALLETBROADCAST));
    {
        LOCK(walletInstance->cs_wallet);
        LogPrintf("setKeyPool.size() = %u\n",      walletInstance->GetKeyPoolSize());
        LogPrintf("mapWallet.size() = %u\n",       walletInstance->mapWallet.size());
        LogPrintf("mapAddressBook.size() = %u\n",  walletInstance->mapAddressBook.size());
    }
    return walletInstance;
}
std::atomic<bool> CWallet::fFlushScheduled(false);
void CWallet::postInitProcess(CScheduler& scheduler)
{
    
    
    ReacceptWalletTransactions();
    
    if (!CWallet::fFlushScheduled.exchange(true)) {
        scheduler.scheduleEvery(MaybeCompactWalletDB, 500);
    }
}
bool CWallet::BackupWallet(const std::string& strDest)