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.

#ifndef BITCOIN_POLICY_POLICY_H
#define BITCOIN_POLICY_POLICY_H
#include "consensus/consensus.h"
#include "script/interpreter.h"
#include "script/standard.h"
#include <string>
class CCoinsViewCache;
static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 0;
static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = 3000000;
static const unsigned int MAX_STANDARD_TX_WEIGHT = 400000;
static const unsigned int MAX_P2SH_SIGOPS = 15;
static const unsigned int MAX_STANDARD_TX_SIGOPS_COST = MAX_BLOCK_SIGOPS_COST/5;
static const unsigned int DEFAULT_MAX_MEMPOOL_SIZE = 300;
/**
 * Standard script verification flags that standard transactions will comply
 * with. However scripts violating these flags may still be present in valid
 * blocks and we must accept those blocks.
 */
static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |