Add dataset to entry on creation

ref-test/app/quiz/views.py

@@ -60,6 +60,7 @@ def _start():
                 write('system.log', f'Database error when processing request \'{request.url}\': {exception}')
                 return abort(500)
             entry.test = test
+            entry.dataset = test.dataset
             entry.user_code = request.form.get('user_code')
             entry.user_code = None if entry.user_code == '' else entry.user_code.lower()
             if not test:  return jsonify({'error': 'The exam code you entered is invalid.'}), 400