Use saved contribution's line items rather than the primaryContributi…

…onID

By the time we reach this point in the code we know that
1) the contributon exists and it has an id
2) it has line items  - either those created in it's pending stage or those calculated in repeattransaction

Therefore we can reasonably assume these line items are accurate now and use them, rather than the confusing
primaryContributionID that we have doubts about the validity of

CRM/Contribute/BAO/Contribution.php

@@ -4510,7 +4510,6 @@ public static function completeOrder($input, &$ids, $objects, $transaction = NUL
       if ($contributionParams['contribution_status_id'] === $completedContributionStatusID) {
         self::updateMembershipBasedOnCompletionOfContribution(
           $contribution,
-          $primaryContributionID,
           $changeDate
         );
       }
@@ -5210,13 +5209,12 @@ protected static function isPaymentInstrumentChange(&$params, $pendingStatuses)
    * load them in this function. Code clean up would compensate for any minor performance implication.
    *
    * @param \CRM_Contribute_BAO_Contribution $contribution
-   * @param int $primaryContributionID
    * @param string $changeDate
    *
    * @throws \CRM_Core_Exception
    * @throws \CiviCRM_API3_Exception
    */
-  public static function updateMembershipBasedOnCompletionOfContribution($contribution, $primaryContributionID, $changeDate) {
+  public static function updateMembershipBasedOnCompletionOfContribution($contribution, $changeDate) {
     $memberships = self::getRelatedMemberships($contribution->id);
     foreach ($memberships as $membership) {
       $membershipParams = [
@@ -5256,7 +5254,7 @@ public static function updateMembershipBasedOnCompletionOfContribution($contribu
         // @todo once apiv4 ships with core switch to that & find sanity.
         $membershipParams['num_terms'] = $contribution->getNumTermsByContributionAndMembershipType(
           $membershipParams['membership_type_id'],
-          $primaryContributionID
+          $contribution->id
         );
       }
       // @todo remove all this stuff in favour of letting the api call further down handle in