Geo secondaries using proxying redirect to primary's internal URL

We've introduced rewriting the Host header in !83550 (merged) however the primary nginx now gets a Host: primary.internal.url as a header, which ends up passed as-is to Rails, which uses it to form the redirects:

root@cat-geo-primary-gitlab-rails-1:~# curl localhost -i -H "Host: test" -s | grep -i location
Location: http://test/users/sign_in

This breaks possibly login and a few other scenarios that are redirecting to an absolute URL when using a Geo secondary.