### Describe the issue

Testing in bitcoin 0.13.0, calling `bitcoin-cli listsinceblock x` is outputting all double-spent transactions that are in the wallet, even those that were double-spent well and truly before x.
### Is the issue reproducible?

Yes
#### List steps to reproduce below:
1.   Create a double-spend send to your wallet (easiest using bip125)
2.   Wait until one confirms, and then wait a few more blocks
3.   Run `bitcoin-cli listsinceblock $(bitcoin-cli getbestblockhash)` and it will output the double spent transaction
### Expected behavior

The double-spent transaction that was conflicted before the block hash should be filtered

}
    if (!pwallet->Unlock(strWalletPass)) {
        throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
    }
    pwallet->TopUpKeyPool();
    pwallet->nRelockTime = GetTime() + nSleepTime;
    
    
    
    std::weak_ptr<CWallet> weak_wallet = wallet;
    pwallet->chain().rpcRunLater(strprintf("lockwallet(%s)", pwallet->GetName()), [weak_wallet] {
        if (auto shared_wallet = weak_wallet.lock()) {
            LOCK(shared_wallet->cs_wallet);
            shared_wallet->Lock();
            shared_wallet->nRelockTime = 0;
        }
    }, nSleepTime);
    return NullUniValue;
}
static UniValue walletpassphrasechange(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"walletpassphrasechange",
                "\nChanges the wallet passphrase from 'oldpassphrase' to 'newpassphrase'.\n",
                {
                    {"oldpassphrase", RPCArg::Type::STR, RPCArg::Optional::NO, "The current passphrase"},