python devShell build fails

[ryneeverett]

Reproducer:

$ cd examples/python_pip-freeze
$ nix build .#devShells.x86_64-linux.default
warning: Git tree '/home/dream2nix' is dirty
error: builder for '/nix/store/fsxzfadk45m01l46cp8nrm4f4dvrp9ks-python3.10-default.drv' failed with exit code 1;
       last 10 log lines:
       > Sourcing python-remove-tests-dir-hook
       > Sourcing python-catch-conflicts-hook.sh
       > Sourcing python-remove-bin-bytecode-hook.sh
       > Sourcing python-imports-check-hook.sh
       > Using pythonImportsCheckPhase
       > Sourcing python-namespaces-hook
       > unpacking sources
       > unpacking source archive .
       > cp: '.' and './.' are the same file
       > do not know how to unpack source archive .
       For full logs, run 'nix log /nix/store/fsxzfadk45m01l46cp8nrm4f4dvrp9ks-python3.10-default.drv'.
error: 1 dependencies of derivation '/nix/store/j85dcaicg01bkzi8q134sidabc3sbng6-nix-shell.drv' failed to build

Workaround:

I can get out-of-tree python devShells building by commenting out the offending src override in subsystems/python/builders/simple-python/default.nix:

    devShell = pkgs.mkShell {
      buildInputs = [
        # a drv with all dependencies without the main package
        (package.overrideAttrs (old: {
          # src = ".";
        }))
      ];
    };

This doesn't fix the example build for me but I assume that's just because I can't figure out how to break dream2nix out of flake cache hell.

[ryneeverett]

I now see that my workaround fails to exclude the main package as the comment indicates it is supposed to and therefore doesn't not yield a shell with an editable installation. After more digging it appears that the regression was introduced in #397 and a more suitable workaround is to revert the relevant bits:

diff --git a/src/subsystems/python/builders/simple-python/default.nix b/src/subsystems/python/builders/simple-python/default.nix
index d9a80dd..98d3d2b 100644
--- a/src/subsystems/python/builders/simple-python/default.nix
+++ b/src/subsystems/python/builders/simple-python/default.nix
@@ -62,13 +62,12 @@
           cp $file dist/$fname
         done
         ${python}/bin/python -m pip install \
-          --find-links ./dist/ \
+          ./dist/*.{whl,tar.gz,zip} \
           --no-build-isolation \
           --no-index \
           --no-warn-script-location \
           --prefix="$out" \
           --no-cache \
-          . \
           $pipInstallFlags
       '';
       installPhase = "true";
@@ -79,6 +78,7 @@
         # a drv with all dependencies without the main package
         (package.overrideAttrs (old: {
           src = ".";
+          dontUnpack = true;
         }))
       ];
     };

[ryneeverett]

Seems like the bigger question is why nix flake check passes yet nix build .#devShells.x86_64-linux.default fails.