Uses proxy_set_header Host $http_host

$http_host is the same as $host, except it also includes the port number if
present in the request.

This is required for valid proxied content rewriting if jenkins_nginx_port is
set to something other than the default port 80.

playbooks/roles/jenkins_master/templates/etc/nginx/sites-available/jenkins.j2

@@ -11,7 +11,7 @@ server {
     # The following settings from https://wiki.jenkins-ci.org/display/JENKINS/Running+Hudson+behind+Nginx
     sendfile off;
 
-    proxy_set_header        Host $host;
+    proxy_set_header        Host $http_host;
     proxy_set_header        X-Real-IP $remote_addr;
     proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
     proxy_connect_timeout   150;