These packages have been "updated in place". That is, our URLs do fetch something with the given version string, but the hash is wrong.
wxwidgets-2.8 gnuplot pardre We have to audit the differences before updating these packages with new hashes. There are still some packages that can't download source code at all: utfcpp slim (found on tarballs.nixos.org) lxtask lxappearance lxrandr libfm lxterminal menu-cache pcmanfm libmng gtkglext freeglut (tarballs.nixos.org) ftgl (tarballs.nixos.org) terminus-font (tarballs.nixos.org) libmodplug (tarballs.nixos.org)