Trick for check_users test without users logged-in

plugins/t/check_users.t

@@ -2,7 +2,11 @@
 #
 # Logged in Users Tests via check_users
 #
+# Trick: This ckeck requires at least 1 user logged in. These commands should
+#        leave a session open forever in the background:
 #
+#   $ ssh -tt localhost </dev/null >/dev/null 2>/dev/null &
+#   $ disown %1
 
 use strict;
 use Test;