AttributeError: 'ProtobufEntry' object has no attribute 'text_payload'

Reproducing this is blocked by #1806, but I wanted to make sure it gets recorded this popped up. Still on `client.list_entries`:

``` python
  File "list_logs.py", line 45, in list_logs
    format((timestamp, entry.text_payload, entry.struct_payload)))
AttributeError: 'ProtobufEntry' object has no attribute 'text_payload'
```
