python3Packages.backports-zoneinfo: patch in zoneinfo and enable tests

pkgs/development/python-modules/backports-zoneinfo/default.nix

@@ -1,6 +1,9 @@
 { lib, buildPythonPackage, fetchFromGitHub
 , pythonOlder
+, python
+, substituteAll
 , importlib-resources
+, tzdata
 , hypothesis
 , pytestCheckHook
 }:
@@ -16,7 +19,17 @@ buildPythonPackage rec {
     sha256 = "sha256-00xdDOVdDanfsjQTd3yjMN2RFGel4cWRrAA3CvSnl24=";
   };
 
-  propagatedBuildInputs = lib.optionals (pythonOlder "3.7") [
+  patches = [
+    (substituteAll {
+      name = "zoneinfo-path";
+      src = ./zoneinfo.patch;
+      zoneinfo = "${tzdata}/lib/${python.libPrefix}/site-packages/tzdata/zoneinfo";
+    })
+  ];
+
+  propagatedBuildInputs = [
+    tzdata
+  ] ++ lib.optionals (pythonOlder "3.7") [
     importlib-resources
   ];
 
@@ -27,8 +40,14 @@ buildPythonPackage rec {
     pytestCheckHook
   ];
 
-  # unfortunately /etc/zoneinfo doesn't exist in sandbox, and many tests fail
-  doCheck = false;
+  disabledTests = [
+    # AssertionError: 'AEDT' != 'AEST'
+    "test_folds_and_gaps"
+    # AssertionError: 0 != 1 : (datetime.datetime(1917, 3, 25, 2, 0, 1, tzinfo=backports.zoneinfo.ZoneInfo(key='Australia/Sydney')), datetime.datetime(1917, 3, 24, 15, 0, tzinfo=datetime.timezone.utc))
+    "test_folds_from_utc"
+    # backports.zoneinfo._common.ZoneInfoNotFoundError: 'No time zone found with key Eurasia/Badzone'
+    "test_bad_keys"
+  ];
 
   meta = with lib; {
     description = "Backport of the standard library module zoneinfo";

pkgs/development/python-modules/backports-zoneinfo/zoneinfo.patch

@@ -0,0 +1,17 @@
+diff --git a/src/backports/zoneinfo/_tzpath.py b/src/backports/zoneinfo/_tzpath.py
+index 9baaf6b..3f842af 100644
+--- a/src/backports/zoneinfo/_tzpath.py
++++ b/src/backports/zoneinfo/_tzpath.py
+@@ -24,10 +24,7 @@ def reset_tzpath(to=None):
+             base_tzpath = _parse_python_tzpath(env_var)
+         elif sys.platform != "win32":
+             base_tzpath = [
+-                "/usr/share/zoneinfo",
+-                "/usr/lib/zoneinfo",
+-                "/usr/share/lib/zoneinfo",
+-                "/etc/zoneinfo",
++                "@zoneinfo@"
+             ]
+ 
+             base_tzpath.sort(key=lambda x: not os.path.exists(x))
+