### 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

auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        const CWallet::TxItems & txOrdered = pwallet->wtxOrdered;
        
        for (CWallet::TxItems::const_reverse_iterator it = txOrdered.rbegin(); it != txOrdered.rend(); ++it)
        {
            CWalletTx *const pwtx = (*it).second;
            ListTransactions(*locked_chain, pwallet, *pwtx, 0, true, ret, filter, filter_label);
            if ((int)ret.size() >= (nCount+nFrom)) break;
        }
    }
    
    if (nFrom > (int)ret.size())
        nFrom = ret.size();
    if ((nFrom + nCount) > (int)ret.size())
        nCount = ret.size() - nFrom;
    std::vector<UniValue> arrTmp = ret.getValues();
    std::vector<UniValue>::iterator first = arrTmp.begin();
    std::advance(first, nFrom);
    std::vector<UniValue>::iterator last = arrTmp.begin();
    std::advance(last, nFrom+nCount);
    if (last != arrTmp.end()) arrTmp.erase(last, arrTmp.end());
    if (first != arrTmp.begin()) arrTmp.erase(arrTmp.begin(), first);
    std::reverse(arrTmp.begin(), arrTmp.end()); 
    ret.clear();
    ret.setArray();
    ret.push_backV(arrTmp);
    return ret;
}
static UniValue listsinceblock(const JSONRPCRequest& request)