Comment 1 for bug 424833

There is an upstream webkit bug about this: https://bugs.webkit.org/show_bug.cgi?id=25263
It has to do with webkit now using the libsoup backend instead of libcurl. This bug is the cause of a heap of applications not working with http proxies. For example Software Centre's screenshots are set as background images in a webkit WebView, so they don't load with an http proxy.