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.

{
            LogPrintf("connected to self at %s, disconnecting\n", pfrom->addr.ToString());
            pfrom->fDisconnect = true;
            return true;
        }
        pfrom->addrLocal = addrMe;
        if (pfrom->fInbound && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }
        
        if (pfrom->fInbound)
            pfrom->PushVersion();
        pfrom->fClient = !(pfrom->nServices & NODE_NETWORK);
        if((pfrom->nServices & NODE_WITNESS))
        {
            LOCK(cs_main);
            State(pfrom->GetId())->fHaveWitness = true;
        }
        
        {
        LOCK(cs_main);
        UpdatePreferredDownload(pfrom, State(pfrom->GetId()));
        }
        
        pfrom->PushMessage(NetMsgType::VERACK);
        pfrom->ssSend.SetVersion(min(pfrom->nVersion, PROTOCOL_VERSION));
        if (!pfrom->fInbound)
        {