Make sure at least one node is given.

tbsetup/sched_reserve.in

@@ -2,7 +2,7 @@
 
 #
 # EMULAB-COPYRIGHT
-# Copyright (c) 2000-2010 University of Utah and the Flux Group.
+# Copyright (c) 2000-2012 University of Utah and the Flux Group.
 # All rights reserved.
 #
 
@@ -38,7 +38,7 @@ delete @ENV{'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};
 
 $| = 1;				#Turn off line buffering on output
 
-if (@ARGV < 2) {
+if (@ARGV < 3) {
   usage();
 }