For software that interfaces with Bitcoin Core via RPC, it can be useful to know whether the fRelayTxes flag is set. It could be added to `getnetworkinfo`.

if (pfrom->nVersion == 10300)
            pfrom->nVersion = 300;
        if (!vRecv.empty())
            vRecv >> addrFrom >> nNonce;
        if (!vRecv.empty()) {
            vRecv >> LIMITED_STRING(pfrom->strSubVer, MAX_SUBVERSION_LENGTH);
            pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
        }
        if (!vRecv.empty()) {
            vRecv >> pfrom->nStartingHeight;
        }
        {
            LOCK(pfrom->cs_filter);
            if (!vRecv.empty())
                vRecv >> pfrom->fRelayTxes; 
            else
                pfrom->fRelayTxes = true;
        }
        
        if (nNonce == nLocalHostNonce && nNonce > 1)
        {
            LogPrintf("connected to self at %s, disconnecting\n", pfrom->addr.ToString());
            pfrom->fDisconnect = true;
            return true;
        }
        pfrom->addrLocal = addrMe;
        if (pfrom->fInbound && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }