Redirects robots.txt using RobotsTxt module

I have the RobotsTxt module that lets me create custom Robots.txt via the web interface for multisite installs. Unfortunately the global redirect kicks in since there is no longer a physical robots.txt file in the root and redirects to "/fr/robots.txt" for example. The search engines will ignore redirects on this file and so Google has stopped indexing the site.

Maybe a special rule which checks the path and stops it is is "robots.txt" ?