Okay, I have this code:

RewriteCond %{HTTPS} off
RewriteCond %{REQUEST_URI} ^/borrowing/ill/request\.php$
RewriteRule ^.*$ https://%{HTTP_HOST}%{REQUEST_URI} [R,L]

The way I would expect this to work is:

1. A request for /borrowing/ill/request.php comes in on HTTP.
2. The rule matches.
3. The server redirects to HTTPS.
4. The rule does not match, because HTTPS is now on.

The way it actually works is:

1. A request for /borrowing/ill/request.php comes in on HTTP.
2. The rule matches.
3. The server redirects to HTTPS.
4. The rule matches.
5. The server redirects to HTTPS.
6. The rule matches.
7. The server redirects to HTTPS ...

And so on.

I know that the second condition (matching the file name) is working, because the redirect loop only hits that specific page. The question is, why isn't the switch to HTTPS causing the first condition to not match?

EDIT:

I put the exact same .htaccess rules into a test area on another server -- same file and path info. And they worked just fine. There's got to be something wrong with the server configuration elsewhere.