EE evaluation license redirects to / instead /gitlab

I'm using external_url 'http://example.com/gitlab/'; in my installation which seems to work really great, the only place it didn't was when I clicked on the button to get a evaluation license, I got redirected back to http://example.com/admin... instead of http://example.com/gitlab/admin...

I saw that and added /gitlab to my URL which allowed me to get the evaluation license, but not everyone will see that.