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.
"                         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).\n"
            "     \"estimate_mode\"     (string, optional, default=UNSET) The fee estimate mode, must be one of:\n"
            "         \"UNSET\"\n"
            "         \"ECONOMICAL\"\n"
            "         \"CONSERVATIVE\"\n"
            "   }\n"
            "\nResult:\n"
            "{\n"
            "  \"txid\":    \"value\",   (string)  The id of the new transaction\n"
            "  \"origfee\":  n,         (numeric) Fee of the replaced transaction\n"
            "  \"fee\":      n,         (numeric) Fee of the new transaction\n"
            "  \"errors\":  [ str... ] (json array of strings) Errors encountered during processing (may be empty)\n"
            "}\n"
            "\nExamples:\n"
            "\nBump the fee, get the new transaction\'s txid\n" +
            HelpExampleCli("bumpfee", "<txid>"));
    }
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VOBJ});
    uint256 hash;
    hash.SetHex(request.params[0].get_str());
    
    CAmount totalFee = 0;
    CCoinControl coin_control;
    coin_control.signalRbf = true;
    if (!request.params[1].isNull()) {