added partial fix for issue #2617. This way double opt in works and the id set before the confirmation mal is sent out.

Author: Peter Halassek

app/code/Magento/Newsletter/Model/Subscriber.php

@@ -442,14 +442,14 @@ public function subscribe($email)
         $this->setStatusChanged(true);
 
         try {
+            $this->save();
             if ($isConfirmNeed === true
                 && $isOwnSubscribes === false
             ) {
                 $this->sendConfirmationRequestEmail();
             } else {
                 $this->sendConfirmationSuccessEmail();
             }
-            $this->save();
             return $this->getStatus();
         } catch (\Exception $e) {
             throw new \Exception($e->getMessage());