allAliases: init

pkgs/top-level/stage.nix

@@ -154,7 +154,22 @@ let
       res self super;
     in res;
 
-  aliases = self: super: lib.optionalAttrs config.allowAliases (import ./aliases.nix lib self super);
+  aliases = self: super:
+    if config.allowAliases
+      then
+        let aliases = import ./aliases.nix lib self super;
+        in aliases // {
+
+          /* Allow generic dependency injection code to avoid aliases, e.g.
+
+              getPkg = name:
+                if ! pkgs?allAliases.${name}
+                then pkgs.${name}
+                else ...
+           */
+          allAliases = lib.mapAttrs (k: v: null) aliases;
+        }
+      else { allAliases = {}; };
 
   # stdenvOverrides is used to avoid having multiple of versions
   # of certain dependencies that were used in bootstrapping the