Broken

POST /edit/share HTTP/1.1
Host: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Connection: keep-alive
Content-Length: 3488
Origin: http://myserver
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.116 Safari/537.36
Content-Type: multipart/form-data, boundary=-------------------------7d76d1b56035e
Accept: */*
DNT: 1
Referer: http://myserver/test.swf
Accept-Encoding: gzip,deflate,sdch
Accept-Language: ja,en;q=0.8,en-US;q=0.6
Cookie: sid=eyJzbnNfY2xpZW50XzAiOnsiYWNjZXNzX3Rva2VuIjoiQ0FBQ0JvTVFycENnQkFEdGJYOTJVMHBVUFJ0MVpBRzBXY2J0bGVNUTJ4dzRqTUFNWDhoQTRTN29uTkNaQ0ZDOE51MjE2OFRJU3pxblpBMkVYcVpBWkF3dDZjc0M0a0Y3N1dmSVdIRm9uWFpCcjI0MllXdWZUOEdVMzJNYTd3R3M3NFNZbXByU08zblQ0WTVlMW1EQXI2bSIsInVzZXJfZGF0YSI6bnVsbH19|1373299692|0590c6bcd67a5544b5af87983dca001340b6972f

---------------------------7d76d1b56035e
Content-Disposition: form-data; name="sns"

0
---------------------------7d76d1b56035e
Content-Disposition: form-data; name="message"

TESTTEST
---------------------------7d76d1b56035e
Content-Disposition: form-data; name="edit_id"

42
---------------------------7d76d1b56035e
Content-Disposition: form-data; name="image"; filename="image"
Content-Type: application/octet-stream

......JFIF...................... a lot of binary data .... 
.(....?..
---------------------------7d76d1b56035e--

Broken output

UnicodeMultiDict([])

Request parameter check

logging.info("%s" % self.request.POST)

Working

POST /edit/share HTTP/1.1
Host: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Connection: keep-alive
Content-Length: 155647
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Origin: http://myserver
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.116 Safari/537.36
Content-Type: multipart/form-data; boundary=----WebKitFormBoundarysMkLNBAe4DVWe3Uy
DNT: 1
Referer: http://myserver/test.html
Accept-Encoding: gzip,deflate,sdch
Accept-Language: ja,en;q=0.8,en-US;q=0.6
Cookie: sid=eyJzbnNfY2xpZW50XzAiOnsiYWNjZXNzX3Rva2VuIjoiQ0FBQ0JvTVFycENnQkFEdGJYOTJVMHBVUFJ0MVpBRzBXY2J0bGVNUTJ4dzRqTUFNWDhoQTRTN29uTkNaQ0ZDOE51MjE2OFRJU3pxblpBMkVYcVpBWkF3dDZjc0M0a0Y3N1dmSVdIRm9uWFpCcjI0MllXdWZUOEdVMzJNYTd3R3M3NFNZbXByU08zblQ0WTVlMW1EQXI2bSIsInVzZXJfZGF0YSI6bnVsbH19|1373299692|0590c6bcd67a5544b5af87983dca001340b6972f

------WebKitFormBoundarysMkLNBAe4DVWe3Uy
Content-Disposition: form-data; name="message"

abcd
------WebKitFormBoundarysMkLNBAe4DVWe3Uy
Content-Disposition: form-data; name="edit_id"

28
------WebKitFormBoundarysMkLNBAe4DVWe3Uy
Content-Disposition: form-data; name="sns"

0
------WebKitFormBoundarysMkLNBAe4DVWe3Uy
Content-Disposition: form-data; name="image"; filename="explanation.png"
Content-Type: image/png

.PNG
.
...
IHDR.......u.....3..0....tEXtSoftware.Adobe ImageReadyq.e<..].IDATx...a.\.}......Pn.|@....lots of binary data .........Mn.yq.W.....IEND.B`.
------WebKitFormBoundarysMkLNBAe4DVWe3Uy--

Working output

UnicodeMultiDict([(u'image', FieldStorage(u'image', u'explanation.png')), (u'message', u'abcd'), (u'edit_id', u'28'), (u'sns', u'0')])