Remove subthemes of an infra theme from update

Remove all subthemes of a centrally managed theme from the Update
manager. This prevents an Undefined index Notice when a locally
installed theme has a centrally managed one as base (e.g., CERN
Overwrite Theme).

See DRUPAL-65

cern_integration.info

 name = CERN Integration
 package = CERN
 description = Provides CERN site integration for Drupal.
-version = "7.X-1.9"
+version = "7.X-1.10"
 core = 7.x
 
 dependencies[] = shib_auth

cern_integration.module

@@ -557,7 +557,9 @@ function  cern_integration_form_domain_301_redirect_admin_form_alter (&$form, &$
 
 /**
  * Implements hook_update_projects_alter().
- * Remove all centrally managed modules and themes from the Update manager.
+ * Remove all centrally managed modules and themes from the Update manager. In addition, remove
+ * all local themes with a centrally managed as base. Because the update manager tries to check
+ * for an update of the base which causes a 'Undefined index' notice.
  */
 function cern_integration_update_projects_alter(&$projects) {
     // Remove all centrally managed modules.
@@ -567,12 +569,24 @@ function cern_integration_update_projects_alter(&$projects) {
             unset($projects[$module]);
         }
     }
-    // Remove all centrally managed themes.
-    foreach (list_themes() as $theme_obj){
+    // Remove all centrally managed themes and their subthemes.
+    $array_themes = list_themes();
+    foreach ($array_themes as $theme_obj) {
         // Check if there is a project for that theme.
         // This is normally true but not always.
         if (isset($theme_obj->info['project'])) {
             if (preg_match('/^sites\/all\/themes\//', $theme_obj->filename)) {
+                // Unset all subthemes.
+                if (property_exists($theme_obj, 'sub_themes')) {
+                    foreach ($theme_obj->sub_themes as $sub_theme_folder_name => $sub_theme_name) {
+                        // Since we can use neither the folder nor the theme name, get the project name if it is still set.
+                        if (isset($array_themes[$sub_theme_folder_name]->info['project'])) {
+                            $sub_theme_project_name = $array_themes[$sub_theme_folder_name]->info['project'];
+                            unset($projects[$sub_theme_project_name]);
+                        }
+                    }
+                }
+                // Unset the centrally managed theme.
                 unset($projects[$theme_obj->info['project']]);
             }
         }