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.

{
public:
    CCoinsViewErrorCatcher(CCoinsView* view) : CCoinsViewBacked(view) {}
    bool GetCoins(const uint256 &txid, CCoins &coins) const {
        try {
            return CCoinsViewBacked::GetCoins(txid, coins);
        } catch(const std::runtime_error& e) {
            uiInterface.ThreadSafeMessageBox(_("Error reading from database, shutting down."), "", CClientUIInterface::MSG_ERROR);
            LogPrintf("Error reading from database: %s\n", e.what());
            
            
            
            
            abort();
        }
    }
    
};
static CCoinsViewDB *pcoinsdbview = NULL;
static CCoinsViewErrorCatcher *pcoinscatcher = NULL;
static boost::scoped_ptr<ECCVerifyHandle> globalVerifyHandle;
void Interrupt(boost::thread_group& threadGroup)