Use URI.decode_www_form_component [Bug #10774]

`parser` refered RFC2396_Parser, but it is separated.
test is contributed by Dominik Menke

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57066 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/uri/mailto.rb

@@ -267,18 +267,18 @@ module URI
     #   # => "To: ruby-list@ruby-lang.org\nSubject: subscribe\nCc: myaddr\n\n\n"
     #
     def to_mailtext
-      to = parser.unescape(@to)
+      to = URI.decode_www_form_component(@to)
       head = ''
       body = ''
       @headers.each do |x|
         case x[0]
         when 'body'
-          body = parser.unescape(x[1])
+          body = URI.decode_www_form_component(x[1])
         when 'to'
-          to << ', ' + parser.unescape(x[1])
+          to << ', ' + URI.decode_www_form_component(x[1])
         else
-          head << parser.unescape(x[0]).capitalize + ': ' +
-            parser.unescape(x[1])  + "\n"
+          head << URI.decode_www_form_component(x[0]).capitalize + ': ' +
+            URI.decode_www_form_component(x[1])  + "\n"
         end
       end
 

test/uri/test_mailto.rb

@@ -187,6 +187,12 @@ class TestMailTo < Test::Unit::TestCase
       u.select(:scheme, :host, :not_exist, :port)
     end
   end
+
+  def test_to_mailtext
+    u = URI.parse('mailto:ruby-list@ruby-lang.org?Subject=subscribe&cc=myaddr')
+    assert_equal "To: ruby-list@ruby-lang.org\nSubject: subscribe\nCc: myaddr\n\n\n",
+      u.to_mailtext
+  end
 end