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.

vGetData.clear();
                }
            } else {
                
                pto->setAskFor.erase(inv.hash);
            }
            pto->mapAskFor.erase(pto->mapAskFor.begin());
        }
        if (!vGetData.empty())
            pto->PushMessage(NetMsgType::GETDATA, vGetData);
        
        
        
        
        if (pto->nVersion >= FEEFILTER_VERSION && GetBoolArg("-feefilter", DEFAULT_FEEFILTER) &&
            !(pto->fWhitelisted && GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY))) {
            CAmount currentFilter = mempool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFeePerK();
            int64_t timeNow = GetTimeMicros();
            if (timeNow > pto->nextSendTimeFeeFilter) {
                CAmount filterToSend = filterRounder.round(currentFilter);
                if (filterToSend != pto->lastSentFeeFilter) {
                    pto->PushMessage(NetMsgType::FEEFILTER, filterToSend);
                    pto->lastSentFeeFilter = filterToSend;
                }
                pto->nextSendTimeFeeFilter = PoissonNextSend(timeNow, AVG_FEEFILTER_BROADCAST_INTERVAL);
            }
            
            
            else if (timeNow + MAX_FEEFILTER_CHANGE_DELAY * 1000000 < pto->nextSendTimeFeeFilter &&
                     (currentFilter < 3 * pto->lastSentFeeFilter / 4 || currentFilter > 4 * pto->lastSentFeeFilter / 3)) {