Add failing test for DDC-2785

Add a failing test for

http://www.doctrine-project.org/jira/browse/DDC-2785
Just ran the tests a couple of times with a `var_dump` right after this line. They were unique every time, e.g.:

```
string(13) "53c3b50c6bff7"
string(13) "53c3b50c6e224"
string(13) "53c3b50c6e322"
```