Comment 2 for bug 1373865

I think it probably is still any issue, although the sequence is probably something like:

- Clean up current backend_ldap (I'll do this)
- split the test_backend apart (samuel is doing this)
- at this point it will be obvious that a lot of what is in test_backend doesn't need multiple domains, so can use a new test fixture
- those that really do need multiple domains can be refactored