Update method for reclass-system review checkout

Change-Id: I02b7fd442002fd67ffdae07fddc0f69bc4bcecc6
Related-Prod: PROD-32736
diff --git a/packer-image-buid.groovy b/packer-image-buid.groovy
index 2cc625b..2e90877 100644
--- a/packer-image-buid.groovy
+++ b/packer-image-buid.groovy
@@ -175,7 +175,11 @@
                             if (reclass_url && reclass_ref) {
                                 if (fileExists('config-drive/model/classes/system')) {
                                     dir('config-drive/model/classes/system') {
-                                        gerrit.gerritPatchsetCheckout(reclass_url, reclass_ref, "HEAD", gerritCredentials)
+                                        checkout([
+                                                $class             : 'GitSCM',
+                                                branches           : [[name: 'FETCH_HEAD']],
+                                                userRemoteConfigs  : [[url: reclass_url, refspec: reclass_ref, credentialsId: gerritCredentials]]
+                                        ])
                                     }
                                 }
                             }