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.

CBlockIndex *pindexBestKnownBlock;
    
    uint256 hashLastUnknownBlock;
    
    CBlockIndex *pindexLastCommonBlock;
    
    CBlockIndex *pindexBestHeaderSent;
    
    int nUnconnectingHeaders;
    
    bool fSyncStarted;
    
    int64_t nStallingSince;
    list<QueuedBlock> vBlocksInFlight;
    
    int64_t nDownloadingSince;
    int nBlocksInFlight;
    int nBlocksInFlightValidHeaders;
    
    bool fPreferredDownload;
    
    bool fPreferHeaders;
    
    bool fPreferHeaderAndIDs;
    
    bool fProvidesHeaderAndIDs;
    
    bool fHaveWitness;
    CNodeState() {