Fix promotion on local storage for aptly

Change-Id: If6663a6d5746fcaa466fc5530c29d2921efeca0b
diff --git a/aptly-promote-pipeline.groovy b/aptly-promote-pipeline.groovy
index 9a5da58..99a07e1 100644
--- a/aptly-promote-pipeline.groovy
+++ b/aptly-promote-pipeline.groovy
@@ -28,6 +28,11 @@
     stage("promote") {
       lock("aptly-api") {
         for (storage in storages) {
+
+          if (storage == "local") {
+            storage = ""
+          }
+
           aptly.promotePublish(APTLY_URL, SOURCE, TARGET, RECREATE, components, packages, DIFF_ONLY, '-d --timeout 600', DUMP_PUBLISH.toBoolean(), storage)
         }
       }