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.

vInv.push_back(CInv(MSG_BLOCK, hash));
                if (vInv.size() == MAX_INV_SZ) {
                    pto->PushMessage(NetMsgType::INV, vInv);
                    vInv.clear();
                }
            }
            pto->vInventoryBlockToSend.clear();
            
            bool fSendTrickle = pto->fWhitelisted;
            if (pto->nNextInvSend < nNow) {
                fSendTrickle = true;
                
                pto->nNextInvSend = PoissonNextSend(nNow, INVENTORY_BROADCAST_INTERVAL >> !pto->fInbound);
            }
            
            if (fSendTrickle) {
                LOCK(pto->cs_filter);
                if (!pto->fRelayTxes) pto->setInventoryTxToSend.clear();
            }
            
            if (fSendTrickle && pto->fSendMempool) {
                auto vtxinfo = mempool.infoAll();
                pto->fSendMempool = false;
                CAmount filterrate = 0;
                {
                    LOCK(pto->cs_feeFilter);
                    filterrate = pto->minFeeFilter;