Handle correctly QUERY_STRING when it's different from REQUEST_URI

Summary:
If the server redirects URLs to a specific query string (the Apache
configuration for Espace Win did exactly that, and /screen/color/879497
can be handled like that too), to remove characters from REQUEST_URI
counting QUERY_STRING doesn't work, as the two diverge.

Ref T1294

Test Plan:

• config: set AllowTopicArticleRequest at true
• nginx: rewrite ^/color/screen/(.+)$ /?Topic=color-screen&Color=$1;

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1294

Differential Revision: https://devcentral.nasqueron.org/D1170