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.

int expired = pool.Expire(GetTime() - age);
    if (expired != 0)
        LogPrint("mempool", "Expired %i transactions from the memory pool\n", expired);
    std::vector<uint256> vNoSpendsRemaining;
    pool.TrimToSize(limit, &vNoSpendsRemaining);
    BOOST_FOREACH(const uint256& removed, vNoSpendsRemaining)
        pcoinsTip->Uncache(removed);
}
std::string FormatStateMessage(const CValidationState &state)
{
    return strprintf("%s%s (code %i)",
        state.GetRejectReason(),
        state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage(),
        state.GetRejectCode());
}
bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const CTransaction& tx, bool fLimitFree,
                              bool* pfMissingInputs, bool fOverrideMempoolLimit, const CAmount& nAbsurdFee,
                              std::vector<uint256>& vHashTxnToUncache)
{
    const uint256 hash = tx.GetHash();
    AssertLockHeld(cs_main);
    if (pfMissingInputs)
        *pfMissingInputs = false;
    if (!CheckTransaction(tx, state))
        return false; 
    
    if (tx.IsCoinBase())