Inaccessible lock files now imply temporary directories can't be removed

Fix #7500

Co-authored-by: Ran Benita <ran@unusedvar.com>

testing/test_pathlib.py

@@ -358,17 +358,25 @@ def test_get_extended_length_path_str():
 
 
 def test_suppress_error_removing_lock(tmp_path):
-    """ensure_deletable should not raise an exception if the lock file cannot be removed (#5456)"""
+    """ensure_deletable should be resilient if lock file cannot be removed (#5456, #7491)"""
     path = tmp_path / "dir"
     path.mkdir()
     lock = get_lock_path(path)
     lock.touch()
     mtime = lock.stat().st_mtime
 
-    with unittest.mock.patch.object(Path, "unlink", side_effect=OSError):
+    with unittest.mock.patch.object(Path, "unlink", side_effect=OSError) as m:
         assert not ensure_deletable(
             path, consider_lock_dead_if_created_before=mtime + 30
         )
+        assert m.call_count == 1
+    assert lock.is_file()
+
+    with unittest.mock.patch.object(Path, "is_file", side_effect=OSError) as m:
+        assert not ensure_deletable(
+            path, consider_lock_dead_if_created_before=mtime + 30
+        )
+        assert m.call_count == 1
     assert lock.is_file()
 
     # check now that we can remove the lock file in normal circumstances