fix access priorities of each level in LeveledOptions (#1118)

Close #1103

lib/puma/configuration.rb

@@ -31,7 +31,7 @@ module Puma
     end
 
     def [](key)
-      @set.each do |o|
+      @set.reverse_each do |o|
         if o.key? key
           return o[key]
         end

test/test_config.rb

@@ -57,6 +57,17 @@ class TestConfigFile < Test::Unit::TestCase
     assert_equal 'bin/rails server', conf.options[:restart_cmd]
   end
 
+  def test_overwrite_options
+    conf = Puma::Configuration.new do |c|
+      c.workers 3
+    end
+    conf.load
+
+    assert_equal conf.options[:workers], 3
+    conf.options[:workers] += 1
+    assert_equal conf.options[:workers], 4
+  end
+
   private
 
     def with_env(env = {})