Merge branch 'MDL-50652_28' of git://github.com/reskit/moodle into MOODLE_28_STABLE

mod/workshop/mod_form.php

@@ -328,7 +328,7 @@ class mod_workshop_mod_form extends moodleform_mod {
      * @return array eventual errors indexed by the field name
      */
     public function validation($data, $files) {
-        $errors = array();
+        $errors = parent::validation($data, $files);
 
         // check the phases borders are valid
         if ($data['submissionstart'] > 0 and $data['submissionend'] > 0 and $data['submissionstart'] >= $data['submissionend']) {