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.

if (!est_filein.IsNull())
        mempool.ReadFeeEstimates(est_filein);
    fFeeEstimatesInitialized = true;
    
#ifdef ENABLE_WALLET
    if (fDisableWallet) {
        pwalletMain = NULL;
        LogPrintf("Wallet disabled!\n");
    } else {
        CWallet::InitLoadWallet();
        if (!pwalletMain)
            return false;
    }
#else 
    LogPrintf("No wallet support compiled in!\n");
#endif 
    
    
    
    if (fPruneMode) {
        LogPrintf("Unsetting NODE_NETWORK on prune mode\n");
        nLocalServices = ServiceFlags(nLocalServices & ~NODE_NETWORK);
        if (!fReindex) {
            uiInterface.InitMessage(_("Pruning blockstore..."));
            PruneAndFlush();
        }
    }
    if (Params().GetConsensus().vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout != 0) {