Why is apache ignoring my [L] flag? I would expect to go to myhost.com/wtf and be taken to myhost.com/mediawiki/index.php without the URL in the browser changing. The problem is that the browser url IS changing, and its maddeningly frustrating.
Here's my simple test rule:
RewriteRule ^/wtf.*$ /mediawiki/index.php [L]
You're omitting the rest of your Apache config or, more likely, the wiki is trying to ensure a canonical URL which isn't configured to the one you want.