Jenkins redirect in Varnish 4

jenkins.vcl

# Jenkins
# This will allow you to run Jenkins as <HOST>/jenkins.

# Varnish 4 declaration
vcl 4.0;

# Backend is using the default Jenkins port.
backend jenkins {
  .host = "127.0.0.1";
  .port = "8080";
}

sub vcl_recv {
    if (req.http.host == "<HOST>" && req.url ~ "/jenkins(/.*)") {
        set req.url = regsub(req.url, "/jenkins(/.*)" , "\1");
        set req.backend_hint = jenkins;
    }
}