From a58cfea20579c1426231e265f715ae90ad925a36 Mon Sep 17 00:00:00 2001
From: Mikhail Golenkov <mikhailgolenkov@catalyst-au.net>
Date: Sun, 26 Apr 2020 10:55:17 +1000
Subject: [PATCH] MDL-67540 quiz: Start transaction before selecting existing
 slots.

Co-authored-by: Conn <conn@cmrwarwicker.com>
---
 mod/quiz/locallib.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mod/quiz/locallib.php b/mod/quiz/locallib.php
index b6f13139cac..b572b633b24 100644
--- a/mod/quiz/locallib.php
+++ b/mod/quiz/locallib.php
@@ -2152,14 +2152,14 @@ function quiz_add_quiz_question($questionid, $quiz, $page = 0, $maxmark = null)
         );
     }
 
+    $trans = $DB->start_delegated_transaction();
     $slots = $DB->get_records('quiz_slots', array('quizid' => $quiz->id),
             'slot', 'questionid, slot, page, id');
     if (array_key_exists($questionid, $slots)) {
+        $trans->allow_commit();
         return false;
     }
 
-    $trans = $DB->start_delegated_transaction();
-
     $maxpage = 1;
     $numonlastpage = 0;
     foreach ($slots as $slot) {