As segwit is active on testnet, blocks will only be downloaded from NODE_WITNESS peers. Though, exactly those peers are disconnected after `BLOCK_STALLING_TIMEOUT = 2` seconds. I am running master (6e6ab2c)

This behavior is consistent across restarts. Sample [debug.log](http://pastebin.ubuntu.com/23058327/) and [getchaintips](http://pastebin.ubuntu.com/23058325/).

It is possible that I shot my own foot at some point, but it seemed smelly enough to create an issue.

}
                LOCK(pto->cs_filter);
                for (const auto& txinfo : vtxinfo) {
                    const uint256& hash = txinfo.tx->GetHash();
                    CInv inv(MSG_TX, hash);
                    pto->setInventoryTxToSend.erase(hash);
                    if (filterrate) {
                        if (txinfo.feeRate.GetFeePerK() < filterrate)
                            continue;
                    }
                    if (pto->pfilter) {
                        if (!pto->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
                    }
                    pto->filterInventoryKnown.insert(hash);
                    vInv.push_back(inv);
                    if (vInv.size() == MAX_INV_SZ) {
                        pto->PushMessage(NetMsgType::INV, vInv);
                        vInv.clear();
                    }
                }
                pto->timeLastMempoolReq = GetTime();
            }
            
            if (fSendTrickle) {
                
                vector<std::set<uint256>::iterator> vInvTx;
                vInvTx.reserve(pto->setInventoryTxToSend.size());
                for (std::set<uint256>::iterator it = pto->setInventoryTxToSend.begin(); it != pto->setInventoryTxToSend.end(); it++) {
                    vInvTx.push_back(it);
                }