rfc - generated cache names are too long #9

What steps will reproduce the problem?
1. create a whole lot of css files
2. include them in a page
3. refresh so that the cache is generated

What is the expected output? What do you see instead?
a file name that the server can render. something like a hash and link the hash 
internally to that long string possibly 

error log:
[Thu Nov 04 01:29:33 2010] [error] [client 127.0.0.1] (36)File name too long: 
access to 
/cc.8d06446468a1b74b8b379d1462beb5a8.assets,_css,_960gs,_960,s+assets,_css,_admi
n_nav,s+assets,_css,_960gs,_uncompressed,_demo,s+assets,_css,_jquery_ui,s+projec
ts,_css,_projects,s+gallery,_css,_gallery,s+gallery,_css,_style_1,s+thickbox,_cs
s,_thickbox,s+contact,_css,_contact,s+comments,_css,_comment,s+filter,_css,_filt
er,s+tags,_css,_tags,s+debug_kit,_css,_debug_toolbar,s.css failed, referer: 
http://dogmatic69.dev/admin

What version of the product are you using? On what operating system?
mod_pagespeed 64-bit .deb ubuntu 10.10 x64 + 5.3.3-1ubuntu9.1 + Apache/2.2.16 
(Ubuntu)

Please provide any additional information below.
long file names generate a 403 Forbidden for anyone else that gets this