How to pass rewritten url to fcgi in lighttpd

Question

I have a redmine instance that runs in the /redmine sub-uri. This is fully working and I can retrieve /redmine/robots.txt without fault.

Adding

url.rewrite = ( "^/robots\.txt$" => "/redmine/robots.txt" )

still gives a 404 error when trying to retrieve /robots.txt.

1. The request in error.log appears identical to GETting /redmine/robots.txt after an initial block changing the url if I turn on debug.log-request-handling = "enable"
2. Using url.rewrite-once does not seem to make a difference.
3. The request never shows up in redmine production.log.

So my question is what I might be missing?