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 (setKeyPool.empty()) {
        return GetTime();
    }
    CKeyPool keypool;
    int64_t nIndex = *(setKeyPool.begin());
    if (!walletdb.ReadPool(nIndex, keypool)) {
        throw std::runtime_error(std::string(__func__) + ": read oldest key in keypool failed");
    }
    assert(keypool.vchPubKey.IsValid());
    return keypool.nTime;
}
int64_t CWallet::GetOldestKeyPoolTime()
{
    LOCK(cs_wallet);
    CWalletDB walletdb(*dbw);
    
    int64_t oldestKey = GetOldestKeyTimeInPool(setExternalKeyPool, walletdb);
    if (IsHDEnabled() && CanSupportFeature(FEATURE_HD_SPLIT)) {
        oldestKey = std::max(GetOldestKeyTimeInPool(setInternalKeyPool, walletdb), oldestKey);
    }
    return oldestKey;
}
std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()