We have tried adding cache-control headers to our proxy but as you've pointed out here, it does not appear to be enough. I've submitted a patch to our cron job that manages the symlinks to update the modified time of the image so that when the browser does an if-modified-since check the time the symlink was created will be used instead of the time the linked file was actually modified.
Let's hope this works! (browser caching is a challenging topic)
We have tried adding cache-control headers to our proxy but as you've pointed out here, it does not appear to be enough. I've submitted a patch to our cron job that manages the symlinks to update the modified time of the image so that when the browser does an if-modified-since check the time the symlink was created will be used instead of the time the linked file was actually modified.
Let's hope this works! (browser caching is a challenging topic)