WIP: more windoes shenanigans

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

Author: jku

tests/test_updater_top_level_update.py

@@ -712,7 +712,7 @@ def test_load_metadata_from_cache(self, wrapped_open: MagicMock) -> None:
         root_dir = os.path.join(self.metadata_dir, "root_history")
         wrapped_open.assert_has_calls(
             [
-                call(os.path.join(self.metadata_dir, ".lock"), "x+b"),
+                call(os.path.join(self.metadata_dir, ".lock"), "wb"),
                 call(os.path.join(root_dir, "2.root.json"), "rb"),
                 call(os.path.join(self.metadata_dir, "timestamp.json"), "rb"),
                 call(os.path.join(self.metadata_dir, "snapshot.json"), "rb"),

tuf/ngclient/updater.py

@@ -172,7 +172,7 @@ def _lock_metadata(self) -> Iterator[None]:
         rootdir = Path(self._dir, "root_history")
         rootdir.mkdir(exist_ok=True, parents=True)
         logger.debug("Getting metadata lock...")
-        with open(os.path.join(self._dir, ".lock"), "a+") as f:
+        with open(os.path.join(self._dir, ".lock"), "wb") as f:
             _lock_file(f)
             yield
         logger.debug("Released metadata lock")