Print message and exit rsync-auto immediately if there is nothing to watch.

plugins/synced_folders/rsync/command/rsync_auto.rb

@@ -70,6 +70,13 @@ module VagrantPlugins
             end
           end
 
+          # Exit immediately if there is nothing to watch
+          if paths.empty?
+            @logger.warn("No paths to listen for so exiting")
+            @env.ui.info(I18n.t("vagrant.rsync_auto_no_paths"))
+            return 1
+          end
+
           # Output to the user what paths we'll be watching
           paths.keys.sort.each do |path|
             paths[path].each do |path_opts|

templates/locales/en.yml

@@ -156,6 +156,8 @@ en:
       Running cleanup tasks for '%{name}' provisioner...
     rsync_auto_initial: |-
       Doing an initial rsync...
+    rsync_auto_no_paths: |-
+      No paths to watch
     rsync_auto_path: |-
       Watching: %{path}
     rsync_communicator_not_ready: |-