From cdac967ea9d6b92f466da0b5d38b560b602b5212 Mon Sep 17 00:00:00 2001
From: Johan Herland <johan@herland.net>
Date: Tue, 15 Jul 2025 15:17:15 +0000
Subject: [PATCH] python3Packages.pytz: use system tzdata

We update that one more reliably, and it allows system-level
customizations to apply to pytz as well. This is in line with the
zoneinfo stdlib module in Python >=v3.9 which accesses the system
timezone database directly.

This is modeled on how the certifi module uses the system-wide
ca-bundle, see commit 8d7cc9cac9ecdf95f554c5ea7ca15118baa06c39.
---
 pkgs/development/python-modules/pytz/default.nix | 12 +++++++++++-
 pkgs/top-level/python-packages.nix               |  4 +++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/python-modules/pytz/default.nix b/pkgs/development/python-modules/pytz/default.nix
index d258ad926ec2..5049c209f088 100644
--- a/pkgs/development/python-modules/pytz/default.nix
+++ b/pkgs/development/python-modules/pytz/default.nix
@@ -3,6 +3,7 @@
   buildPythonPackage,
   fetchPypi,
   setuptools,
+  tzdata,
   unittestCheckHook,
 }:
 
@@ -16,6 +17,12 @@ buildPythonPackage rec {
     hash = "sha256-NguePbtJognCGtYYCcf7RTZD4EiziSTHZYE1RnRugcM=";
   };
 
+  postPatch = ''
+    # Use our system-wide zoneinfo dir instead of the bundled one
+    rm -rf pytz/zoneinfo
+    ln -snvf ${tzdata}/share/zoneinfo pytz/zoneinfo
+  '';
+
   build-system = [ setuptools ];
 
   nativeCheckInputs = [ unittestCheckHook ];
@@ -32,6 +39,9 @@ buildPythonPackage rec {
     description = "World timezone definitions, modern and historical";
     homepage = "https://pythonhosted.org/pytz";
     license = licenses.mit;
-    maintainers = with maintainers; [ dotlambda ];
+    maintainers = with maintainers; [
+      dotlambda
+      jherland
+    ];
   };
 }
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index e398e398f8a4..71d84a38372a 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -15008,7 +15008,9 @@ self: super: with self; {
 
   pytweening = callPackage ../development/python-modules/pytweening { };
 
-  pytz = callPackage ../development/python-modules/pytz { };
+  pytz = callPackage ../development/python-modules/pytz {
+    inherit (pkgs) tzdata;
+  };
 
   pytz-deprecation-shim = callPackage ../development/python-modules/pytz-deprecation-shim { };