### 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

#include <amount.h>
#include <core_io.h>
#include <init.h>
#include <interfaces/chain.h>
#include <key_io.h>
#include <outputtype.h>
#include <policy/feerate.h>
#include <policy/fees.h>
#include <policy/rbf.h>
#include <rpc/rawtransaction_util.h>
#include <rpc/server.h>
#include <rpc/util.h>
#include <script/descriptor.h>
#include <script/sign.h>
#include <util/bip32.h>
#include <util/fees.h>
#include <util/moneystr.h>
#include <util/string.h>
#include <util/system.h>
#include <util/url.h>
#include <util/validation.h>
#include <wallet/coincontrol.h>
#include <wallet/feebumper.h>
#include <wallet/psbtwallet.h>
#include <wallet/rpcwallet.h>
#include <wallet/wallet.h>
#include <wallet/walletdb.h>
#include <wallet/walletutil.h>
#include <stdint.h>