sending a shutdown command to kill a node seems a lot more reliable than issuing a kill command (on my system anyways)

test/tools/repl_set_manager.rb

@@ -187,9 +187,11 @@ class ReplSetManager
   def kill(node, signal=2)
     pid = @mongods[node]['pid']
     puts "** Killing node with pid #{pid} at port #{@mongods[node]['port']}"
-    system("kill -#{signal} #{@mongods[node]['pid']}")
+    begin
+      get_connection(node)['admin'].command({'shutdown' => 1})
+    rescue Mongo::ConnectionFailure
+    end
     @mongods[node]['up'] = false
-    sleep(1)
   end
 
   def kill_primary(signal=2)