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.

{
            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);
        }
        
        if (pfrom->fInbound)
            pfrom->PushVersion();
        pfrom->fClient = !(pfrom->nServices & NODE_NETWORK);
        if((pfrom->nServices & NODE_WITNESS))
        {
            LOCK(cs_main);
            State(pfrom->GetId())->fHaveWitness = true;
        }
        
        {
        LOCK(cs_main);
        UpdatePreferredDownload(pfrom, State(pfrom->GetId()));
        }
        
        pfrom->PushMessage(NetMsgType::VERACK);
        pfrom->ssSend.SetVersion(min(pfrom->nVersion, PROTOCOL_VERSION));
        if (!pfrom->fInbound)
        {