Comment 1 for bug 1366651

It looks like this has been introduced as part of this fix:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718639

" * debian/conf/fastcgi_params:
     + Sync with upstream and remove `SCRIPT_FILENAME` parameter.
       This change might break fastcgi sites. (Closes: #718639)"

Definitely not something that should be put in a patch release...