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