### 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

"The command will fail if the wallet or mempool contains a transaction that spends one of T's outputs.\n"
                "By default, the new fee will be calculated automatically using estimatesmartfee.\n"
                "The user can specify a confirmation target for estimatesmartfee.\n"
                "Alternatively, the user can specify totalFee (DEPRECATED), or fee_rate (" + CURRENCY_UNIT + " per kB) for the new transaction .\n"
                "At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee\n"
                "returned by getnetworkinfo) to enter the node's mempool.\n",
                {
                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The txid to be bumped"},
                    {"options", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "",
                        {
                            {"confTarget", RPCArg::Type::NUM,  "wallet default", "Confirmation target (in blocks)"},
                            {"totalFee", RPCArg::Type::NUM,  "fallback to 'confTarget'", "Total fee (NOT feerate) to pay, in satoshis. (DEPRECATED)\n"
            "                         In rare cases, the actual fee paid might be slightly higher than the specified\n"
            "                         totalFee if the tx change output has to be removed because it is too close to\n"
            "                         the dust threshold."},
                            {"fee_rate", RPCArg::Type::NUM,  "fallback to 'confTarget'", "FeeRate (NOT total fee) to pay, in " + CURRENCY_UNIT + " per kB\n"
            "                         Specify a fee rate instead of relying on the built-in fee estimator.\n"
            "                         Must be at least 0.0001 BTC per kB higher than the current transaction fee rate.\n"},
                            {"replaceable", RPCArg::Type::BOOL,  "true", "Whether the new transaction should still be\n"
            "                         marked bip-125 replaceable. If true, the sequence numbers in the transaction will\n"
            "                         be left unchanged from the original. If false, any input sequence numbers in the\n"
            "                         original transaction that were less than 0xfffffffe will be increased to 0xfffffffe\n"
            "                         so the new transaction will not be explicitly bip-125 replaceable (though it may\n"
            "                         still be replaceable in practice, for example if it has unconfirmed ancestors which\n"
            "                         are replaceable)."},
                            {"estimate_mode", RPCArg::Type::STR,  "UNSET", "The fee estimate mode, must be one of:\n"
            "         \"UNSET\"\n"
            "         \"ECONOMICAL\"\n"
            "         \"CONSERVATIVE\""},
                        },