crash when removing a replica
    
    when a server is removed from the topology the plugin tries to remove the
    credentials from the replica and the bind dn group.
    It performs an internal search for the ldap principal, but can fail if it was already removed
    Due to an unitialized variable in this case it can eitehr crash or erroneously remove all
    principals.
    
    Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>