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.
{
    AssertLockHeld(cs_wallet); 
    setLockedCoins.clear();
}
bool CWallet::IsLockedCoin(uint256 hash, unsigned int n) const
{
    AssertLockHeld(cs_wallet); 
    COutPoint outpt(hash, n);
    return (setLockedCoins.count(outpt) > 0);
}
void CWallet::ListLockedCoins(std::vector<COutPoint>& vOutpts) const
{
    AssertLockHeld(cs_wallet); 
    for (std::set<COutPoint>::iterator it = setLockedCoins.begin();
         it != setLockedCoins.end(); it++) {
        COutPoint outpt = (*it);
        vOutpts.push_back(outpt);
    }
}
 
void CWallet::GetKeyBirthTimes(std::map<CTxDestination, int64_t> &mapKeyBirth) const {
    AssertLockHeld(cs_wallet); 
    mapKeyBirth.clear();
    
    for (const auto& entry : mapKeyMetadata) {
        if (entry.second.nCreateTime) {
            mapKeyBirth[entry.first] = entry.second.nCreateTime;