--- a/mercurial/store.py	Wed Dec 04 17:13:39 2024 +0100
+++ b/mercurial/store.py	Wed Dec 04 23:31:46 2024 +0100
@@ -460,6 +460,9 @@
     unencoded_path = attr.ib()
     _file_size = attr.ib(default=None)
     is_volatile = attr.ib(default=False)
+    # Missing file can be safely ignored, used by "copy/hardlink" local clone
+    # for cache file not covered by lock.
+    optional = False
 
     def file_size(self, vfs):
         if self._file_size is None: