Apache - RewriteEngine must be on

Issue Summary

I tracked down a bug in my setup that caused Redirect Loops for some pages when non-clean to clean redirection was enabled in global redirect. In this case, it happened because request_uri() was returning a non-clean url even though user was on a clean url. So in the end, http://foo.com/example kepts redirecting to http://foo.com/example.

It turns out request_uri() was not returning the clean path because $_SERVER['SCRIPT_URI'] and $_SERVER['REQUEST_URI'] were not set. This happens if you don't have "RewriteEngine On" globally or in a virtual host definition. Once that is enabled, then those server variables get populated, and for me the redirect loops stopped occurring.

I hope this helps someone else.