Drop-in replacement support for get-version-suffix

pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh invokes this.
Probably it should not?

diff --git a/nixos/modules/installer/tools/get-version-suffix b/nixos/modules/installer/tools/get-version-suffix
new file mode 100755 (executable)
index 0000000..fceb513
--- /dev/null
+++ b/nixos/modules/installer/tools/get-version-suffix
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+echo "warning: Using legacy channel get-version-suffix from `nix-instantiate --find-file nixpkgs-warned "$@"`/nixos/modules/installer/tools/get-version-suffix" >&2
+
+/bin/sh `nix-instantiate --find-file nixpkgs-warned "$@"`/nixos/modules/installer/tools/get-version-suffix "$@"