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.

int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
                                 bool poolHasNoInputsOf, CAmount _inChainInputValue,
                                 bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp):
    tx(std::make_shared<CTransaction>(_tx)), nFee(_nFee), nTime(_nTime), entryPriority(_entryPriority), entryHeight(_entryHeight),
    hadNoDependencies(poolHasNoInputsOf), inChainInputValue(_inChainInputValue),
    spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp)
{
    nTxWeight = GetTransactionWeight(_tx);
    nModSize = _tx.CalculateModifiedSize(GetTxSize());
    nUsageSize = RecursiveDynamicUsage(*tx) + memusage::DynamicUsage(tx);
    nCountWithDescendants = 1;
    nSizeWithDescendants = GetTxSize();
    nModFeesWithDescendants = nFee;
    CAmount nValueIn = _tx.GetValueOut()+nFee;
    assert(inChainInputValue <= nValueIn);
    feeDelta = 0;
    nCountWithAncestors = 1;
    nSizeWithAncestors = GetTxSize();
    nModFeesWithAncestors = nFee;
    nSigOpCostWithAncestors = sigOpCost;
}
CTxMemPoolEntry::CTxMemPoolEntry(const CTxMemPoolEntry& other)