Fixed checkouting in test nodejs pipeline

Change-Id: I84c2379a842d53fdbf287482f4c4e0883e3f2339
diff --git a/test-nodejs-pipeline.groovy b/test-nodejs-pipeline.groovy
index f6e91ef..d0365a4 100644
--- a/test-nodejs-pipeline.groovy
+++ b/test-nodejs-pipeline.groovy
@@ -45,7 +45,7 @@
         stage('Checkout source code') {
             if (gerritRef) {
                 // job is triggered by Gerrit
-                gerrit.gerritPatchsetCheckout ([
+                checkouted = gerrit.gerritPatchsetCheckout ([
                     credentialsId : CREDENTIALS_ID,
                     withWipeOut : true,
                 ])