Bug#1094663: $PATH not set properly in gnome

[David Mandelberg]

Package: nix-setup-systemd
Version: 2.8.0-1.1

If I'm understanding it correctly, 
/usr/lib/environment.d/nix-daemon.conf sets $PATH, but then 
/usr/bin/gnome-session starts a login shell, which sources /etc/profile 
on startup, which resets $PATH to a default value.

Related: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=869144

Would it make sense for nix-setup-systemd to set $PATH somewhere else? 
Or maybe the default /etc/profile should be changed?