Allowing form error string to be unescaped (bug #1203082)

As the string is hardcoded in lang file and does NOT take any variables
it is ok to pass into form error as unescaped.

Change-Id: Ibc0b9d7ed872abb7c4ba77d3d2bb5abcde110abc
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/auth/lib.php

@@ -1836,7 +1836,7 @@ function password_validate(Pieform $form, $values, $user) {
     $authobj = AuthFactory::create($user->authinstance);
 
     if (!$form->get_error('password1') && !$authobj->is_password_valid($values['password1'])) {
-        $form->set_error('password1', get_string('passwordinvalidform', "auth.$authobj->type"));
+        $form->set_error('password1', get_string('passwordinvalidform', "auth.$authobj->type"), false);
     }
 
     $suckypasswords = array(