Bring an importable modulesPath back from the dead, in the only way I know

lib/modules.nix

@@ -17,6 +17,10 @@ rec {
      evalModules) and the less declarative the module set is. */
   evalModules = { modules
                 , prefix ? []
+                , # This should only be used for special arguments that need to be evaluated
+                  # when resolving module structure (like in imports). For everything else,
+                  # there's _module.args.
+                  specialArgs ? {}
                 , # This would be remove in the future, Prefer _module.args option instead.
                   args ? {}
                 , # This would be remove in the future, Prefer _module.check option instead.
@@ -51,7 +55,7 @@ rec {
         };
       };
 
-      closed = closeModules (modules ++ [ internalModule ]) { inherit config options; lib = import ./.; };
+      closed = closeModules (modules ++ [ internalModule ]) (specialArgs // { inherit config options; lib = import ./.; });
 
       # Note: the list of modules is reversed to maintain backward
       # compatibility with the old module system.  Not sure if this is
@@ -118,7 +122,7 @@ rec {
         config = removeAttrs m ["key" "_file" "require" "imports"];
       };
 
-  applyIfFunction = f: arg@{ config, options, lib }: if isFunction f then
+  applyIfFunction = f: arg@{ config, options, lib, ... }: if isFunction f then
     let
       # Module arguments are resolved in a strict manner when attribute set
       # deconstruction is used.  As the arguments are now defined with the

nixos/lib/eval-config.nix

@@ -47,6 +47,7 @@ in rec {
     inherit prefix check;
     modules = modules ++ extraModules ++ baseModules ++ [ pkgsModule ];
     args = extraArgs;
+    specialArgs = { modulesPath = ../modules; };
   }) config options;
 
   # These are the extra arguments passed to every module.  In

nixos/modules/misc/extra-arguments.nix

@@ -2,8 +2,6 @@
 
 {
   _module.args = {
-    modulesPath = ../.;
-
     pkgs_i686 = import ../../lib/nixpkgs.nix {
       system = "i686-linux";
       config.allowUnfree = true;