Reported here: https://github.com/bitcoin/bitcoin/pull/10244#issuecomment-378035305

Travis log here: https://travis-ci.org/bitcoin/bitcoin/jobs/361243719#L2810

Note the JSON exception:

```
test_framework.authproxy.JSONRPCException: The mempool was not loaded yet (-1) 
```

That exception was introduced here: https://github.com/bitcoin/bitcoin/commit/cb1e319fe9e198c9c5cf5236fe9af5a3d748b9e8#diff-a0c8f511d90e83aa9b5857e819ced344R1617

cc @jtimon 
indexed_disconnected_transactions queuedTx;
    uint64_t cachedInnerUsage = 0;
    
    
    size_t DynamicMemoryUsage() const {
        return memusage::MallocUsage(sizeof(CTransactionRef) + 6 * sizeof(void*)) * queuedTx.size() + cachedInnerUsage;
    }
    void addTransaction(const CTransactionRef& tx)
    {
        queuedTx.insert(tx);
        cachedInnerUsage += RecursiveDynamicUsage(tx);
    }
    
    void removeForBlock(const std::vector<CTransactionRef>& vtx)