If you run this test a few times for instance passing in `-Dtests.iters=10` you'll get a couple of failures like this one:
```
java.lang.AssertionError: expected [2xx] status code but api [cat.fielddata] returned [500 Internal Server Error] [{"error":"ElasticsearchIllegalStateException[mismatch on number of cells 5 in a row compared to header 6]","status":500}]
```

Seems like an actual bug?