Help me!!! About Content-Type header parse

[goosman.lei]

When I used multipart/form-data, I find that:
1. Content-Type: multipart/form-data;
boundary=----------------------------4db878605894\r\n
2. Content-Type: multipart/form-data;
boundary=----------------------------4db878605894; charset=utf-8\r\n
3. Content-Type: multipart/form-data; charset=utf-8;
boundary=----------------------------4db878605894\r\n

in above three example, when I submit 1 and 3, It's work fine, but 2 don't
work

Is there a bug? or who can tell me why?

demonstrate code: http://pastebin.com/59aAhkFY

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,233848,233848#msg-233848