--- a/mercurial/revlogutils/revlogv0.py	Tue May 04 11:19:48 2021 +0200
+++ b/mercurial/revlogutils/revlogv0.py	Tue May 04 14:16:26 2021 +0200
@@ -42,6 +42,7 @@
 
 
 class revlogoldindex(list):
+    rust_ext_compat = 0
     entry_size = INDEX_ENTRY_V0.size
     null_item = (
         0,