Waiting list does not check that all regular slots are used

Hello,

In case I have an entity with 2 slots +1 in the waiting list enabled, registration_status() returns false if there is one (non wait list) registration and one (wait list) registration. This can happen in case a user who register on the main list then cancel/delete his registration. In my opinion, it should return true since the total number of slots have not been filled yet.

To do so, replace (in waiting_list.module)

<?php
    // We only need to check how many people are on the waitlist if there is a capacity other than 0 set
    if ($active && $waitlist_capacity) {
      $waitlist_state = registration_get_states(REGISTRATION_WAITLIST_STATE);
      // get count of registrations with the waitlist state
      $query = db_select('registration', 'r');
      $query->addExpression('sum(count)', 'count');
      $query->condition('entity_id', $entity_id);
      $query->condition('entity_type', $entity_type);
      $query->condition('state', $waitlist_state->identifier());
      $result = $query->execute();
      $waitlist_count = $result->fetchField();
      $waitlist_count = ($waitlist_count == '') ? 0 : $waitlist_count;

      if (($waitlist_capacity - $waitlist_count) < 1) {
        $active = FALSE;
        $errors[] = t('waitlist is full');
      }
    }
?>

by

<?php
    // We only need to check how many people are on the waitlist if there is a capacity other than 0 set
    if ($active && $waitlist_capacity) {
      $waitlist_state = registration_get_states(REGISTRATION_WAITLIST_STATE);
      $canceled_state = registration_get_states('canceled');      
      // get count of registrations with the waitlist state
      $query = db_select('registration', 'r');
      $query->addExpression('sum(count)', 'count');
      $query->condition('entity_id', $entity_id);
      $query->condition('entity_type', $entity_type);
//       $query->condition('state', $waitlist_state->identifier());
      $query->condition('state', $canceled_state->identifier(), '<>');
      $result = $query->execute();
      $total_count = $result->fetchField();
      $total_count = ($total_count == '') ? 0 : $total_count;

      // compare the total number of registrations to the sum of capacity and waiting list capacity
      // allow to handle the case where normal applications have been deleted.
      if (($capacity + $waitlist_capacity - $total_count) < 1) {
        $active = FALSE;
        $errors[] = t('waitlist is full');
      }
    }
?>

Please tell me if it is a bug or if it works as designed.

EDIT: patch provided.