Wrong assumption about rules_install()

In rules_include() the module checks for the presence of rules_install() to decide if to use the data contained in the cache.
That function could exist even when the module is not being installed, as a call to drupal_get_schema() causes rules.install to be included.

    //During installation we can't use the cache as the table isn't there yet
    $use_cache = !function_exists('rules_install');
    
    if ($type == 'rules_admin') {
      $files = array(drupal_get_path('module', 'rules') .'/rules.admin.inc');
    }