Funky cache path name is generated for rss( feed.rss.rss )

Rails
1

In my routes.rb, I have
map.all_product_feed ‘/feed.rss’, :controller => ‘product’, :action =>
‘rss’

in my ProductController, I use action cache:
caches_action :rss

if I access http://localtest.com/product/rss, the log shows that the
action is cached as localtest.com/feed.rss

but when I access http://localtest.com/feed.rss, the log shows that the
action is cached as localtest.com/feed.rss.rss.

when I edit a product which causes a cache sweeper to run, only the
cache localtest.com/products.rss got deleted.

so I am getting stale data when accessing http://localtest.com/feed.rss.

Is there a way to control the cache path/key?

Is this a bug in rails where an extra “.rss” is appended?

Thanks.