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.
if (nFeePerK > HIGH_TX_FEE_PER_KB)
            InitWarning(AmountHighWarn("-paytxfee") + " " +
                        _("This is the transaction fee you will pay if you send a transaction."));
        payTxFee = CFeeRate(nFeePerK, 1000);
        if (payTxFee < ::minRelayTxFee)
        {
            return InitError(strprintf(_("Invalid amount for -paytxfee=<amount>: '%s' (must be at least %s)"),
                                       GetArg("-paytxfee", ""), ::minRelayTxFee.ToString()));
        }
    }
    if (IsArgSet("-maxtxfee"))
    {
        CAmount nMaxFee = 0;
        if (!ParseMoney(GetArg("-maxtxfee", ""), nMaxFee))
            return InitError(AmountErrMsg("maxtxfee", GetArg("-maxtxfee", "")));
        if (nMaxFee > HIGH_MAX_TX_FEE)
            InitWarning(_("-maxtxfee is set very high! Fees this large could be paid on a single transaction."));
        maxTxFee = nMaxFee;
        if (CFeeRate(maxTxFee, 1000) < ::minRelayTxFee)
        {
            return InitError(strprintf(_("Invalid amount for -maxtxfee=<amount>: '%s' (must be at least the minrelay fee of %s to prevent stuck transactions)"),
                                       GetArg("-maxtxfee", ""), ::minRelayTxFee.ToString()));
        }
    }
    nTxConfirmTarget = GetArg("-txconfirmtarget", DEFAULT_TX_CONFIRM_TARGET);
    bSpendZeroConfChange = GetBoolArg("-spendzeroconfchange", DEFAULT_SPEND_ZEROCONF_CHANGE);
    fWalletRbf = GetBoolArg("-walletrbf", DEFAULT_WALLET_RBF);
    return true;
}
bool CWallet::BackupWallet(const std::string& strDest)