[X-Pack] Login after session timeout does not direct user back to previously viewed page with reverse proxy

[inqueue]

Kibana version:
5.6.9 w/X-Pack Security enabled
Kibana is behind a reverse proxy.

Elasticsearch version:
5.6.9

Browser version:
Version 66.0.3359.181 (Official Build) (64-bit)

Describe the bug:
Login after session timeout does not direct the browser back to the page where the timeout was reached when Kibana is behind a reverse proxy.

Steps to reproduce:

1. Put Kibana behind a reverse proxy and configure server.basePath: "/kibana" in kibana.yml. Configure reverse proxy accordingly.
2. Configure xpack.security.sessionTimeout: 10000 in kibana.yml (sets the session timeout to 10s)
3. Login to Kibana, goto Dev Tools and wait 10 seconds.
4. After the session expires, login with credentials used in step 3.
5. Observe the browser lands on the default app after login and not Dev Tools.

Expected behavior:
Browser is directed back to Dev Tools.

Screenshots (if relevant):

Errors in browser console (if relevant):
none

Any additional context:
Does not reproduce in the default configuration without reverse proxy; i.e., server.basePath unset. Issue reproduces with or without SSL enabled at the reverse proxy.

nginx config:

server {
  listen       6601;
  listen       4601 ssl;
  server_name  localhost;
  ssl_certificate      localhost.pem;
  ssl_certificate_key  localhost.key;
  ssl_session_cache    shared:SSL:1m;
  ssl_session_timeout  5m;
  ssl_ciphers  HIGH:!aNULL:!MD5;
  ssl_prefer_server_ciphers  on;

  location /kibana {
    proxy_pass  http://localhost:5601/;
    rewrite ^/kibana/(.*)$ /$1 break;
  }
}

kibana.yml:

xpack.security.sessionTimeout: 10000
server.basePath: "/kibana"

[chandlermelton]

This configuration was working as intended in version 5.1.2.

[kobelb]

Duplicate of #22440