CONTRIB-4052 Prevent gradebook entry from being added when using nograde

preferences.php

@@ -93,7 +93,9 @@ switch ($att->pageparams->action) {
         foreach ($acronym as $id => $v) {
             $att->update_status($id, $acronym[$id], $description[$id], $grade[$id], null);
         }
+        if ($att->grade > 0) {
             att_update_all_users_grades($att->id, $att->course, $att->context, $cm);
+        }
         break;
 }
 

sessions.php

@@ -85,7 +85,9 @@ switch ($att->pageparams->action) {
 
         if (isset($confirm) && confirm_sesskey()) {
             $att->delete_sessions(array($sessionid));
+            if ($att->grade > 0) {
                 att_update_all_users_grades($att->id, $att->course, $att->context, $cm);
+            }
             redirect($att->url_manage(), get_string('sessiondeleted', 'attendance'));
         }
 
@@ -112,7 +114,9 @@ switch ($att->pageparams->action) {
             $sessionsids = explode('_', $sessionsids);
 
             $att->delete_sessions($sessionsids);
+            if ($att->grade > 0) {
                 att_update_all_users_grades($att->id, $att->course, $att->context, $cm);
+            }
             redirect($att->url_manage(), get_string('sessiondeleted', 'attendance'));
         }
         $sessid = required_param('sessid', PARAM_SEQUENCE);