fix test if unsufficient resources

Previously the test would generate an error if the default partition
  contained less than 3 nodes
bug 1720

testsuite/expect/test1.97

@@ -285,6 +285,12 @@ proc submit_tasks {ntasks ntaskpn} {
 }
 
 ######################## Test Starts Here ########################
+set def_part_name [default_partition]
+set nb_nodes [get_node_cnt_in_part $def_part_name]
+if {$nb_nodes < 3} {
+	send_user "\nWARNING: This test requires at least 3 nodes in the cluster.\n"
+	exit $exit_code
+}
 
 make_bash_script $file_in "true"