Tests try to enable twice xmlsitemap.module

The code for setUp() contained in the helper class contains the following code:

function setUp() {
    // Call parent::setUp() allowing test cases to pass further modules.
    $modules = func_get_args();
    $modules[] = 'xmlsitemap';
    call_user_func_array(array($this, 'parent::setUp'), $modules);

The same function contained in the classes derived from that contains parent::setUp('xmlsitemap'), with the result that the array <code>$modules will contain the same module name twice.

Also, it should probably better to add xmlsitemap at the top of the array, in the case the subclass is trying to add a module that depends from xmlsitemap.module. As far as I can understand, SimpleTest doesn't enables the modules respecting the dependencies between them (or is it that done from Drupal core code?).