Ask salt to return a proper exit code so we can fail the builder appropriately.

provisioner/salt-masterless/provisioner.go

@@ -181,7 +181,7 @@ func (p *Provisioner) Provision(ui packer.Ui, comm packer.Communicator) error {
 	}
 
 	ui.Message("Running highstate")
-	cmd := &packer.RemoteCmd{Command: "sudo salt-call --local state.highstate -l info"}
+	cmd := &packer.RemoteCmd{Command: "sudo salt-call --local state.highstate -l info --retcode-passthrough"}
 	if err = cmd.StartWithUi(comm, ui); err != nil || cmd.ExitStatus != 0 {
 		if err == nil {
 			err = fmt.Errorf("Bad exit status: %d", cmd.ExitStatus)