I don't really understand nix-env's resolution rules

.circleci/config.yml

@@ -170,7 +170,7 @@ jobs:
       - run:
           name: "Set up Cachix"
           command: |
-            nix-env -f $NIXPKGS -iA nixpkgs.cachix nixpkgs.bash
+            nix-env -f $NIXPKGS -iA cachix bash
             cachix use "${CACHIX_NAME}"
             nix path-info --all > /tmp/store-path-pre-build