fix feedsearch-crawler to build outside of overlay

integrations/nur/default.nix

@@ -10,6 +10,18 @@
 #
 # to manually query available packages, modules, etc, try:
 # - nix eval --impure --expr 'builtins.attrNames (import ./. {})'
+#
+# to validate this before a push that would propagate to NUR:
+#   NIX_PATH= NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-env -f . -qa \* --meta --xml \
+#     --allowed-uris https://static.rust-lang.org \
+#     --option restrict-eval true \
+#     --option allow-import-from-derivation true \
+#     --drv-path --show-trace \
+#     -I nixpkgs=$(nix-instantiate --find-file nixpkgs) \
+#     -I ../../
+# ^ source: <https://github.com/nix-community/nur-packages-template/blob/master/.github/workflows/build.yml#L63>
+#   N.B.: nur eval allows only PATH (inherited) and NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM="1" (forced),
+#   hence the erasing of NIX_PATH above (to remove external overlays)
 
 { pkgs ? import <nixpkgs> {} }:
 let

pkgs/default.nix

@@ -1,5 +1,9 @@
 { pkgs ? import <nixpkgs> {}, lib ? pkgs.lib, unpatched ? pkgs }:
 let
+
+  pythonPackagesOverlay = py-final: py-prev: import ./python-packages {
+    inherit (py-final) callPackage;
+  };
   # this scope ensures that my packages can all take each other as inputs,
   # even when evaluated bare (i.e. outside of an overlay)
   sane = lib.makeScope pkgs.newScope (self: with self; {
@@ -58,10 +62,12 @@ let
 
     ### PYTHON PACKAGES
     pythonPackagesExtensions = (unpatched.pythonPackagesExtensions or []) ++ [
-      (py-final: py-prev: import ./python-packages { inherit (py-final) callPackage; })
+      pythonPackagesOverlay
     ];
     # when this scope's applied as an overlay pythonPackagesExtensions is propagated as desired.
     # but when freestanding (e.g. NUR), it never gets plumbed into the outer pkgs, so we have to do that explicitly.
-    pythonInterpreters = unpatched.pythonInterpreters.override { inherit pythonPackagesExtensions; };
+    python3 = unpatched.python3.override {
+      packageOverrides = pythonPackagesOverlay;
+    };
   });
 in sane.packages sane