send push on addMagnetDownload success only

src/public/download.php

@@ -63,8 +63,8 @@ else if (is_null($user->public))
 else
 {
   // Register magnet download
-  $magnetDownloadId = $db->addMagnetDownload($magnet->magnetId, $user->userId, time());
-
+  if ($magnetDownloadId = $db->addMagnetDownload($magnet->magnetId, $user->userId, time()))
+  {
     // Push event to other nodes
     if (API_EXPORT_ENABLED &&
         API_EXPORT_PUSH_ENABLED &&
@@ -87,6 +87,7 @@ else
 
       $memory->set('api.export.push', $memoryApiExportPush, 3600);
     }
+  }
 
   // Build magnet link
   $link = (object)