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.

assert(fImporting == true);
        fImporting = false;
    }
};
void CleanupBlockRevFiles()
{
    using namespace boost::filesystem;
    map<string, path> mapBlockFiles;
    
    
    
    LogPrintf("Removing unusable blk?????.dat and rev?????.dat files for -reindex with -prune\n");
    path blocksdir = GetDataDir() / "blocks";
    for (directory_iterator it(blocksdir); it != directory_iterator(); it++) {
        if (is_regular_file(*it) &&
            it->path().filename().string().length() == 12 &&
            it->path().filename().string().substr(8,4) == ".dat")
        {
            if (it->path().filename().string().substr(0,3) == "blk")
                mapBlockFiles[it->path().filename().string().substr(3,5)] = it->path();
            else if (it->path().filename().string().substr(0,3) == "rev")
                remove(it->path());
        }
    }
    
    
    
    
    int nContigCounter = 0;
    BOOST_FOREACH(const PAIRTYPE(string, path)& item, mapBlockFiles) {