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.

#include "main.h"
#include "addrman.h"
#include "arith_uint256.h"
#include "blockencodings.h"
#include "chainparams.h"
#include "checkpoints.h"
#include "checkqueue.h"
#include "consensus/consensus.h"
#include "consensus/merkle.h"
#include "consensus/validation.h"
#include "hash.h"
#include "init.h"
#include "merkleblock.h"
#include "net.h"
#include "policy/fees.h"
#include "policy/policy.h"
#include "pow.h"