[GR-49675] Re-enable chown gid test on Darwin

Author: timfel

graalpython/lib-python/3/test/test_os.py

@@ -1859,9 +1859,9 @@ def test_chown_uid_gid_arguments_must_be_index(self):
         self.assertIsNone(os.chown(os_helper.TESTFN, -1, -1))
 
     @unittest.skipUnless(hasattr(os, 'getgroups'), 'need os.getgroups')
-    @unittest.skipIf(sys.platform == 'darwin', 'transiently fails on darwin: GR-49675')
     def test_chown_gid(self):
-        groups = os.getgroups()
+        # Exclude the all-ones gid, which chown treats as "do not change group".
+        groups = [gid for gid in os.getgroups() if gid != (1 << 32) - 1]
         if len(groups) < 2:
             self.skipTest("test needs at least 2 groups")