[Bug 1769677] Re: gnome-software reads system proxy settings in a wrong way

** Description changed: After setting a proxy (e.g. http proxy) in Settings, gnome-software will show a message saying something like `E: https://mirrors.ustc.edu.cn/ubuntu bionic/universe amd64 libkf5archive5 amd64 5.44.0-0ubuntu1 is not (yet) available (Unsupported proxy

[Bug 1769677] [NEW] gnome-software reads system proxy settings in a wrong way

Public bug reported: After setting a proxy (e.g. http proxy) in Settings, gnome-software will show a message saying something like `E: https://mirrors.ustc.edu.cn/ubuntu bionic/universe amd64 libkf5archive5 amd64 5.44.0-0ubuntu1 is not (yet) available (Unsupported proxy configured: