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.

{
    assert(pindex->GetBlockHash() == view.GetBestBlock());
    if (pfClean)
        *pfClean = false;
    bool fClean = true;
    CBlockUndo blockUndo;
    CDiskBlockPos pos = pindex->GetUndoPos();
    if (pos.IsNull())
        return error("DisconnectBlock(): no undo data available");
    if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash()))
        return error("DisconnectBlock(): failure reading undo data");
    if (blockUndo.vtxundo.size() + 1 != block.vtx.size())
        return error("DisconnectBlock(): block and undo data inconsistent");
    
    for (int i = block.vtx.size() - 1; i >= 0; i--) {
        const CTransaction &tx = block.vtx[i];
        uint256 hash = tx.GetHash();
        
        
        {
        CCoinsModifier outs = view.ModifyCoins(hash);
        outs->ClearUnspendable();
        CCoins outsBlock(tx, pindex->nHeight);