Fix change-proxy.sh: honor UID=0 for system changes.
Fix change-proxy.sh: honor UID=0 for system changes.

blueyed/dotfiles,blueyed/dotfiles,blueyed/dotfiles,blueyed/dotfiles,scorpiovn/dotfiles,scorpiovn/dotfiles,scorpiovn/dotfiles,blueyed/dotfiles,scorpiovn/dotfiles,scorpiovn/dotfiles