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.

NotifyHeaderTip();
    }
    else if (strCommand == NetMsgType::BLOCK && !fImporting && !fReindex) 
    {
        CBlock block;
        vRecv >> block;
        LogPrint("net", "received block %s peer=%d\n", block.GetHash().ToString(), pfrom->id);
        CValidationState state;
        
        
        
        
        bool forceProcessing = pfrom->fWhitelisted && !IsInitialBlockDownload();
        ProcessNewBlock(state, chainparams, pfrom, &block, forceProcessing, NULL);
        int nDoS;
        if (state.IsInvalid(nDoS)) {
            assert (state.GetRejectCode() < REJECT_INTERNAL); 
            pfrom->PushMessage(NetMsgType::REJECT, strCommand, (unsigned char)state.GetRejectCode(),
                               state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), block.GetHash());
            if (nDoS > 0) {
                LOCK(cs_main);
                Misbehaving(pfrom->GetId(), nDoS);
            }
        }
    }
    else if (strCommand == NetMsgType::GETADDR)
    {