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.

if (it->second->nHeight < chainActive.Height() - 15) {
            LogPrint("net", "Peer %d sent us a getblocktxn for a block > 15 deep", pfrom->id);
            return true;
        }
        CBlock block;
        assert(ReadBlockFromDisk(block, it->second, chainparams.GetConsensus()));
        BlockTransactions resp(req);
        for (size_t i = 0; i < req.indexes.size(); i++) {
            if (req.indexes[i] >= block.vtx.size()) {
                Misbehaving(pfrom->GetId(), 100);
                LogPrintf("Peer %d sent us a getblocktxn with out-of-bounds tx indices", pfrom->id);
                return true;
            }
            resp.txn[i] = block.vtx[req.indexes[i]];
        }
        pfrom->PushMessageWithFlag(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCKTXN, resp);
    }
    else if (strCommand == NetMsgType::GETHEADERS)
    {
        CBlockLocator locator;
        uint256 hashStop;
        vRecv >> locator >> hashStop;
        LOCK(cs_main);
        if (IsInitialBlockDownload() && !pfrom->fWhitelisted) {
            LogPrint("net", "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom->id);
            return true;
        }
        CNodeState *nodestate = State(pfrom->GetId());
        CBlockIndex* pindex = NULL;
        if (locator.IsNull())