Add failing test for DDC-2785

Add a failing test for

http://www.doctrine-project.org/jira/browse/DDC-2785
Well, for starters, the `$oid` is present in `$this->entityStates`. There is also one element in `$this->identityMap` which has the same oid, but a different phonenumber. I added this debugging code to the beginning of `getEntityState()`:

```
foreach ($this->identityMap['Doctrine\Tests\Models\CMS\CmsPhonenumber'] as $object)
{
     var_dump(spl_object_hash($entity));
     var_dump(spl_object_hash($object));
     var_dump($object->phonenumber);
     var_dump($entity->phonenumber);
}
```

Output:
```
string(32) "00000000747296c9000000005e37a61c"
string(32) "00000000747296ad000000005e37a61c"
string(13) "53c3cfcc6cb2f"
string(13) "53c3cfcc6cc25"
```

Is this the information you were looking for?