fix: correctly calculate next cycle end date for memberships that are prolonged

src/QUI/Memberships/Users/MembershipUser.php

@@ -122,7 +122,11 @@ public function extend($auto = true, \DateTime $NextBeginDate = null, \DateTime
     {
         // Calculate new start and/or end time
         if (empty($NextBeginDate)) {
-            $NextBeginDate = $this->getNextCycleBeginDate();
+            if (MembershipUsersHandler::getExtendMode() === MembershipUsersHandler::EXTEND_MODE_PROLONG) {
+                $NextBeginDate = $this->getCycleBeginDate();
+            } else {
+                $NextBeginDate = $this->getNextCycleBeginDate();
+            }
         }
 
         if (empty($NextEndDate)) {
@@ -1286,10 +1290,6 @@ public function getNextCycleBeginDate()
             return false;
         }
 
-        if (MembershipUsersHandler::getExtendMode() === MembershipUsersHandler::EXTEND_MODE_PROLONG) {
-            return $this->getCycleBeginDate();
-        }
-
         $NextBeginDate = clone $EndDate;
 
         switch (MembershipUsersHandler::getDurationMode()) {