in v0.12 https://github.com/bitcoin/bitcoin/pull/7081 (by @luke-jr) was merged adding `-bytespersigop` (with default of 20).

this is preventing simple bare multisig transactions from being accepted into mempool when the size is < 400 bytes.  
eg; https://gist.github.com/rubensayshi/ac4f617207f7a50559e85d61c05800be

from 1-of-7 and onwards they are accepted because the ratio of bytes:sigops is high enough.  
also having 2 or more inputs will work because it again tips the ratio of bytes:sigops over.

the reason mainly being that `GetLegacySigOpCount` calls `GetSigOpCount` with `fAccurate=false`.

It looks like changing `GetLegacySigOpCount` to use `fAccurate=true` would cause side effects in the few other places (`ConnectBlock`, `CheckBlock`, `CreateNewBlock`) and simply adding `fAccurate` as arg to `GetLegacySigOpCount` would affect the value stored in `CTxMemPoolEntry.sigOpCount` which in turn affects a bunch of other things.

}
    else if (strCommand == NetMsgType::TX)
    {
        
        
        if (!fRelayTxes && (!pfrom->fWhitelisted || !GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY)))
        {
            LogPrint("net", "transaction sent in violation of protocol peer=%d\n", pfrom->id);
            return true;
        }
        deque<COutPoint> vWorkQueue;
        vector<uint256> vEraseQueue;
        CTransaction tx;
        vRecv >> tx;
        CInv inv(MSG_TX, tx.GetHash());
        pfrom->AddInventoryKnown(inv);
        LOCK(cs_main);
        bool fMissingInputs = false;
        CValidationState state;
        pfrom->setAskFor.erase(inv.hash);
        mapAlreadyAskedFor.erase(inv.hash);
        if (!AlreadyHave(inv) && AcceptToMemoryPool(mempool, state, tx, true, &fMissingInputs)) {
            mempool.check(pcoinsTip);
            RelayTransaction(tx);
            for (unsigned int i = 0; i < tx.vout.size(); i++) {
                vWorkQueue.emplace_back(inv.hash, i);
            }
            pfrom->nLastTXTime = GetTime();
            LogPrint("mempool", "AcceptToMemoryPool: peer=%d: accepted %s (poolsz %u txn, %u kB)\n",
                pfrom->id,