Removed the "charset" parameter from the Content-Type header of multipart...

Removed the "charset" parameter from the Content-Type header of multipart sections of nested multipart messages.
Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#2109 state:committed]

actionmailer/lib/action_mailer/part.rb

@@ -88,7 +88,10 @@ def to_mail(defaults)
           part.parts << prt
         end
         
-        part.set_content_type(real_content_type, nil, ctype_attrs) if real_content_type =~ /multipart/
+        if real_content_type =~ /multipart/
+          ctype_attrs.delete 'charset'
+          part.set_content_type(real_content_type, nil, ctype_attrs)
+        end
       end
 
       headers.each { |k,v| part[k] = v }

actionmailer/test/mail_service_test.rb

@@ -330,6 +330,7 @@ def test_nested_parts
     assert_equal "multipart/mixed", created.content_type
     assert_equal "multipart/alternative", created.parts.first.content_type
     assert_equal "bar", created.parts.first.header['foo'].to_s
+    assert_nil created.parts.first.charset
     assert_equal "text/plain", created.parts.first.parts.first.content_type
     assert_equal "text/html", created.parts.first.parts[1].content_type
     assert_equal "application/octet-stream", created.parts[1].content_type