Make packer debug faster

Change-Id: Ief29d1b742f88b5979a7628889d1511d2c8eb0b1
diff --git a/common/ubuntu_salt_bootstrap.sh b/common/ubuntu_salt_bootstrap.sh
index ad3757e..b691d4d 100644
--- a/common/ubuntu_salt_bootstrap.sh
+++ b/common/ubuntu_salt_bootstrap.sh
@@ -1,5 +1,10 @@
 #!/bin/bash -xe
 
+if [ -f '/tmp/done_ubuntu_salt_bootstrap' ]; then
+  echo "INFO: ubuntu_salt_bootstrap already finished! Skipping.."
+  exit 0
+fi
+#
 CLUSTER_NAME=${CLUSTER_NAME:-lost_cluster_name_variable}
 CLUSTER_MODEL=${CLUSTER_MODEL:-https://github.com/Mirantis/mcp-offline-model.git}
 CLUSTER_MODEL_REF=${CLUSTER_MODEL_REF:-master}
@@ -56,3 +61,4 @@
   exit 1
 fi
 bash -x /srv/salt/scripts/bootstrap.sh || true
+touch /tmp/done_ubuntu_salt_bootstrap