default.nix: Provide correct instructions how to upgrade Nix

dezgeg · dezgeg · commit 2e91b2d585af · 2017-03-18T21:04:07.000+02:00
Supersedes NixOS#17631.
diff --git a/default.nix b/default.nix
@@ -2,7 +2,17 @@ let requiredVersion = import ./lib/minver.nix; in
 
 if ! builtins ? nixVersion || builtins.compareVersions requiredVersion builtins.nixVersion == 1 then
 
-  abort "This version of Nixpkgs requires Nix >= ${requiredVersion}, please upgrade! See https://nixos.org/wiki/How_to_update_when_Nix_is_too_old_to_evaluate_Nixpkgs"
+  abort ''
+
+    This version of Nixpkgs requires Nix >= ${requiredVersion}, please upgrade:
+
+    - If you are running NixOS, use `nixos-rebuild' to upgrade your system.
+
+    - If you installed Nix using the install script (https://nixos.org/nix/install),
+      it is safe to upgrade by running it again:
+
+          curl https://nixos.org/nix/install | sh
+  ''
 
 else
 
