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.

{
    const std::string URL_SOURCE_CODE = "<https:github.com/bitcoin/bitcoin>";
    const std::string URL_WEBSITE = "<https:bitcoincore.org>";
    
    return CopyrightHolders(strprintf(_("Copyright (C) %i-%i"), 2009, COPYRIGHT_YEAR) + " ") + "\n" +
           "\n" +
           strprintf(_("Please contribute if you find %s useful. "
                       "Visit %s for further information about the software."),
               PACKAGE_NAME, URL_WEBSITE) +
           "\n" +
           strprintf(_("The source code is available from %s."),
               URL_SOURCE_CODE) +
           "\n" +
           "\n" +
           _("This is experimental software.") + "\n" +
           _("Distributed under the MIT software license, see the accompanying file COPYING or <http:www.opensource.org/licenses/mit-license.php>.") + "\n" +
           "\n" +
           _("This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit <https:www.openssl.org/> and cryptographic software written by Eric Young and UPnP software written by Thomas Bernard.") +
           "\n";
}
static void BlockNotifyCallback(bool initialSync, const CBlockIndex *pBlockIndex)