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.

{
            boost::this_thread::interruption_point();
            if ((addr.nServices & REQUIRED_SERVICES) != REQUIRED_SERVICES)
                continue;
            if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)
                addr.nTime = nNow - 5 * 24 * 60 * 60;
            pfrom->AddAddressKnown(addr);
            bool fReachable = IsReachable(addr);
            if (addr.nTime > nSince && !pfrom->fGetAddr && vAddr.size() <= 10 && addr.IsRoutable())
            {
                
                {
                    LOCK(cs_vNodes);
                    
                    
                    static const uint64_t salt0 = GetRand(std::numeric_limits<uint64_t>::max());
                    static const uint64_t salt1 = GetRand(std::numeric_limits<uint64_t>::max());
                    uint64_t hashAddr = addr.GetHash();
                    multimap<uint64_t, CNode*> mapMix;
                    const CSipHasher hasher = CSipHasher(salt0, salt1).Write(hashAddr << 32).Write((GetTime() + hashAddr) / (24*60*60));
                    BOOST_FOREACH(CNode* pnode, vNodes)