python313Packages.langchain: fix build

Shell tool defaults to `/bin/bash`.

pkgs/development/python-modules/langchain/default.nix

@@ -21,6 +21,9 @@
   sqlalchemy,
   tenacity,
 
+  # runtime
+  runtimeShell,
+
   # tests
   blockbuster,
   freezegun,
@@ -54,6 +57,11 @@ buildPythonPackage rec {
 
   sourceRoot = "${src.name}/libs/langchain_v1";
 
+  postPatch = ''
+    substituteInPlace langchain/agents/middleware/shell_tool.py \
+      --replace-fail '"/bin/bash"' '"${runtimeShell}"'
+  '';
+
   build-system = [ hatchling ];
 
   pythonRelaxDeps = [