Error after upgrading to Drupal 7.43: "Undefined index: args in DatabaseLog..."

After upgrading from Drupal 7.41 to Drupal 7.43, I found that my Views are producing the following notice error when using PHP contextual filter code:

Notice: Undefined index: args in DatabaseLog->findCaller() (line 156 of .../includes/database/log.inc).

By debugging, I know that this is produced by PHP contextual filter in Views. Specifically by line 53 of views/plugins/views_plugin_argument_default_php.inc

Below is my PHP contextual filter code:

  $filter = array();
  if (module_exists('mymodule')) {
    $url = drupal_get_path_alias(current_path());
    $query = db_query(
    'SELECT cp.contact_person_id
     FROM {mymodule_table} cp
     WHERE cp.website_section_url LIKE :url_to_find', array(':url_to_find' => $url));
    foreach ($query as $row) {
      $filter[] = $row->contact_person_id;
    }
  }
  return implode('+',$filter);

The SQL query works correctly.
The view is a Block.

What could be happening?