mod_pagespeed_beacon returns 404 with VirtualHost #177

What steps will reproduce the problem?
1. install mod_pagespeed from trunk src 
2. mod_pagespeed_beacon got 404 while visit any page of my site


What is the expected output? What do you see instead?
Expect a 204 No Content


What version of the product are you using (please check X-Mod-Pagespeed
header)?

X-Mod-Pagespeed 0.9.0.0-349

Please provide any additional information below, especially a URL or an
HTML file that exhibits the problem.


on my test 0.9.13.1 didn't have this issue.

0.9.14.2 & 0.9.14.3 didn't has this issue.

but 0.9.14.3 with wrong version number (0.9.14.0-349)

0.9.14.1 can't compile complete due to lack of url_pollable_async_fetcher.h.

all of above using same config