id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
27328	return `Set-Cookie` if sessionid=  None value	Ramin Farajpour Cami	nobody	"Hi,

i use request AJAX, when i haven't sessionid i can send request i see response 


{{{
POST http://IP/session HTTP/1.1
Host: IP
Connection: keep-alive
Content-Length: 0
Accept: application/json, text/javascript, */*; q=0.01
Origin: http://IP
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36
X-CSRFToken: BF8nOVWsMJaX9Gi3aJijGSO97iTyLpNY
Referer: http://172.16.20.141/ramin
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.8
Cookie: sessionid=;csrftoken=BF8nOVWsMJaX9Gi3aJijGSO97iTyLpNY

}}}

you see here `Cookie: sessionid=;csrftoken=BF8nOVWsMJaX9Gi3aJijGSO97iTyLpNY` sessionid is ` sessionid=` send to django server 


{{{
HTTP/1.1 200 OK
Date: Sun, 09 Oct 2016 08:17:15 GMT
Content-Type: application/json
Connection: keep-alive
Set-Cookie: sessionid=; expires=Thu, 01-Jan-1970 00:00:00 GMT; Max-Age=0; Path=/
Content-Length: 18

}}}

set `Set-Cookie: sessionid=; expires=Thu, 01-Jan-1970 00:00:00 GMT; Max-Age=0; Path=/` in response django
i see your code [https://github.com/django/django/blob/master/django/http/cookie.py#L74] in if `val` is empty , you need change `or` to `and`,


"	Cleanup/optimization	closed	contrib.sessions	1.10	Normal	needsinfo		Collin Anderson	Unreviewed	1	0	0	0	0	0