SPDY + proxy cache = occasional 499 errors

[spdyg]

Hi there,

I have been piloting the SPDY patch on a separate web server pointing to an
existing HTTP backend.

With just myself using this pilot web server, occasionally static resources
such as css or images are not loading in Firefox (usually when pressing F5
to reload a page)

Have done a bit of digging and have learnt this so far:

When issue occurs in Firefox, access log is showing 499 errors for the
missing static resources (when it should be 304)
Refreshing the page will eventually load the resources (and they will show
304 in the access log)
If I turn off the proxy cache for these static resources, the issue stops
If I turn off SPDY, the issue stops.
The issue obviously doesn't occur on the production web server running Nginx
1.2.x

Has this been seen before, or can you think of any reason why this might
happen?

I don't normally use Chrome but have also witnessed this once in Chrome, so
I don't think it's browser specific (however will try to get more confidence
of this).

Thanks.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,233461,233461#msg-233461