python3Packages.pythonImportsCheck: set $PYTHONPATH

Don't rely on the installPhase doing so.

pkgs/development/interpreters/python/hooks/default.nix

@@ -93,7 +93,7 @@ in {
     makePythonHook {
       name = "python-imports-check-hook.sh";
       substitutions = {
-        inherit pythonCheckInterpreter;
+        inherit pythonCheckInterpreter pythonSitePackages;
       };
     } ./python-imports-check-hook.sh) {};
 

pkgs/development/interpreters/python/hooks/python-imports-check-hook.sh

@@ -6,6 +6,7 @@ pythonImportsCheckPhase () {
 
     if [ -n "$pythonImportsCheck" ]; then
         echo "Check whether the following modules can be imported: $pythonImportsCheck"
+        export PYTHONPATH="$out/@pythonSitePackages@:$PYTHONPATH"
         ( cd $out && eval "@pythonCheckInterpreter@ -c 'import os; import importlib; list(map(lambda mod: importlib.import_module(mod), os.environ[\"pythonImportsCheck\"].split()))'" )
     fi
 }