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(%s, %u bytes): Exception '%s' caught\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
            }
            else if (strstr(e.what(), "non-canonical ReadCompactSize()"))
            {
                
                LogPrintf("%s(%s, %u bytes): Exception '%s' caught\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
            }
            else
            {
                PrintExceptionContinue(&e, "ProcessMessages()");
            }
        }
        catch (const boost::thread_interrupted&) {
            throw;
        }
        catch (const std::exception& e) {
            PrintExceptionContinue(&e, "ProcessMessages()");
        } catch (...) {
            PrintExceptionContinue(NULL, "ProcessMessages()");
        }
        if (!fRet)
            LogPrintf("%s(%s, %u bytes) FAILED peer=%d\n", __func__, SanitizeString(strCommand), nMessageSize, pfrom->id);
        break;
    }
    
    if (!pfrom->fDisconnect)
        pfrom->vRecvMsg.erase(pfrom->vRecvMsg.begin(), it);
    return fOk;
}
class CompareInvMempoolOrder