Merge branch 'MDL-51837-28' of git://github.com/junpataleta/moodle into MOODLE_28_STABLE

user/editadvanced_form.php

@@ -272,7 +272,7 @@ class user_editadvanced_form extends moodleform {
             }
         }
 
-        if (!$user or $user->email !== $usernew->email) {
+        if (!$user or (isset($usernew->email) && $user->email !== $usernew->email)) {
             if (!validate_email($usernew->email)) {
                 $err['email'] = get_string('invalidemail');
             } else if ($DB->record_exists('user', array('email' => $usernew->email, 'mnethostid' => $CFG->mnet_localhost_id))) {