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 
{
    std::vector<indexed_transaction_set::const_iterator> iters;
    AssertLockHeld(cs);
    iters.reserve(mapTx.size());
    for (indexed_transaction_set::iterator mi = mapTx.begin(); mi != mapTx.end(); ++mi) {
        iters.push_back(mi);
    }
    std::sort(iters.begin(), iters.end(), DepthAndScoreComparator());
    return iters;
}
void CTxMemPool::queryHashes(std::vector<uint256>& vtxid) const
{
    LOCK(cs);
    auto iters = GetSortedDepthAndScore();
    vtxid.clear();
    vtxid.reserve(mapTx.size());
    for (auto it : iters) {
        vtxid.push_back(it->GetTx().GetHash());
    }
}
static TxMempoolInfo GetInfo(CTxMemPool::indexed_transaction_set::const_iterator it) {