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("%s: parameter interaction: -connect set -> setting -dnsseed=0\n", __func__);
        if (SoftSetBoolArg("-listen", false))
            LogPrintf("%s: parameter interaction: -connect set -> setting -listen=0\n", __func__);
    }
    if (mapArgs.count("-proxy")) {
        
        if (SoftSetBoolArg("-listen", false))
            LogPrintf("%s: parameter interaction: -proxy set -> setting -listen=0\n", __func__);
        
        
        if (SoftSetBoolArg("-upnp", false))
            LogPrintf("%s: parameter interaction: -proxy set -> setting -upnp=0\n", __func__);
        
        if (SoftSetBoolArg("-discover", false))
            LogPrintf("%s: parameter interaction: -proxy set -> setting -discover=0\n", __func__);
    }
    if (!GetBoolArg("-listen", DEFAULT_LISTEN)) {
        
        if (SoftSetBoolArg("-upnp", false))
            LogPrintf("%s: parameter interaction: -listen=0 -> setting -upnp=0\n", __func__);
        if (SoftSetBoolArg("-discover", false))
            LogPrintf("%s: parameter interaction: -listen=0 -> setting -discover=0\n", __func__);
        if (SoftSetBoolArg("-listenonion", false))
            LogPrintf("%s: parameter interaction: -listen=0 -> setting -listenonion=0\n", __func__);
    }
    if (mapArgs.count("-externalip")) {
        
        if (SoftSetBoolArg("-discover", false))
            LogPrintf("%s: parameter interaction: -externalip set -> setting -discover=0\n", __func__);
    }