server {
        listen domainB:8080;
        server_name domainB;

        access_log   /var/log/nginx/domainB.access.log;
        error_log    /var/log/nginx/domainB.error.log;

        location / {
                root /var/www/domainB;
                try_files $uri @static;
        }

        location @static {
            proxy_cookie_domain domain domainB;
            proxy_pass_header Set-Cookie;
            proxy_set_header Accept-Encoding "";
            proxy_set_header      Host     domain;
            proxy_pass http://mymo;

            proxy_redirect http://domain/ http://domainB:8080/;
            proxy_redirect https://domain/ http://domainB:8080/;
        }
}

http {
        .....
        upstream mymo { server domain; }
        ......

➜  ~ curl -I http://domainB:8080/
HTTP/1.1 301 Moved Permanently
Server: nginx/1.4.6 (Ubuntu)
Date: Wed, 04 May 2016 08:38:03 GMT
Content-Type: text/html;charset=UTF-8
Connection: keep-alive
Set-Cookie: JSESSIONID=425E88911934F6E2A94DC91751D25B9E; Path=/; HttpOnly
Location: /personal.do
Vary: Accept-Encoding

➜  ~ curl -I http://domainB:8080/personal.do
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.4.6 (Ubuntu)
Date: Wed, 04 May 2016 08:39:48 GMT
Content-Type: text/html
Connection: keep-alive
Set-Cookie: JSESSIONID=823C9BB2BEDAF871A8090C86EDC0B990; Path=/; HttpOnly
Set-Cookie: ID=425109; Expires=Thu, 04-May-2017 08:39:50 GMT; Path=/
Pragma: No-cache
Cache-Control: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Location: http://domainB:8080/goLogin.do;jsessionid=823C9BB2BEDAF871A8090C86EDC0B990
Vary: Accept-Encoding

➜  ~ curl -I http://domainB:8080/goLogin.do;jsessionid=823C9BB2BEDAF871A8090C86EDC0B990
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.4.6 (Ubuntu)
Date: Wed, 04 May 2016 08:41:20 GMT
Content-Type: text/html
Connection: keep-alive
Pragma: No-cache
Cache-Control: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Location: http://domainB:8080/goLogin.do;jsessionid=823C9BB2BEDAF871A8090C86EDC0B990;jsessionid=823C9BB2BEDAF871A8090C86EDC0B990
Vary: Accept-Encoding