There is an assert in `CWalletTx::RelayWalletTransaction` that gets hit.  All other code paths check `fBroadcastTransactions` before getting to `CWallet::ResendWalletTransactionsBefore` except the rpc call `resendwalletransactions`.

It's an easy fix, but we just need to decide whether to throw an error or return an empty array of rebroadcasted transaction ids.

Should be fixed for 0.15.
"    \"txid\" : \"transactionid\",     (string) The transaction id locked\n"
            "    \"vout\" : n                      (numeric) The vout value\n"
            "  }\n"
            "  ,...\n"
            "]\n"
            "\nExamples:\n"
            "\nList the unspent transactions\n"
            + HelpExampleCli("listunspent", "") +
            "\nLock an unspent transaction\n"
            + HelpExampleCli("lockunspent", "false \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"") +
            "\nList the locked transactions\n"
            + HelpExampleCli("listlockunspent", "") +
            "\nUnlock the transaction again\n"
            + HelpExampleCli("lockunspent", "true \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"") +
            "\nAs a json rpc call\n"
            + HelpExampleRpc("listlockunspent", "")
        );
    LOCK2(cs_main, pwallet->cs_wallet);
    std::vector<COutPoint> vOutpts;
    pwallet->ListLockedCoins(vOutpts);
    UniValue ret(UniValue::VARR);
    for (COutPoint &outpt : vOutpts) {
        UniValue o(UniValue::VOBJ);
        o.push_back(Pair("txid", outpt.hash.GetHex()));
        o.push_back(Pair("vout", (int)outpt.n));
        ret.push_back(o);
    }
    return ret;
}
UniValue settxfee(const JSONRPCRequest& request)