test(update): qualify download retries on native Windows

Signed-off-by: BigDataDZ <76271875+BigDataDZ@users.noreply.github.com>

Author: BigDataDZ

.github/workflows/python-tests.yml

@@ -819,6 +819,7 @@ jobs:
           tests/control_plane/test_effect_runtime_integration.py
           tests/control_plane/test_shadow_observation_retirement.py
           tests/test_self_update_runtime_activation.py
+          tests/test_self_update_download.py
           tests/test_windows_atomic_writes.py
           tests/test_windows_install.py
 

tests/test_self_update_download.py

@@ -1,3 +1,4 @@
+import os
 import subprocess
 from pathlib import Path
 
@@ -19,7 +20,10 @@ def run(args, **kwargs):
         if args[0] == "curl":
             script = Path(args[args.index("--output") + 1])
             assert script.read_bytes() == b""
-            assert script.stat().st_mode & 0o777 == 0o600
+            # Windows does not expose POSIX owner-only permission bits. Keep
+            # that assertion on POSIX; partial-byte and retry checks run on both.
+            if os.name != "nt":
+                assert script.stat().st_mode & 0o777 == 0o600
             if len(calls) == 1:
                 script.write_text("echo PARTIAL_SECRET")
                 return subprocess.CompletedProcess(