diff -r 84b176ad2860 -r c261899fb282 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Mon May 03 12:19:09 2021 +0200
+++ b/mercurial/debugcommands.py	Mon May 03 12:20:25 2021 +0200
@@ -793,7 +793,7 @@
     index = r.index
     start = r.start
     length = r.length
-    generaldelta = r.version & revlog.FLAG_GENERALDELTA
+    generaldelta = r._generaldelta
     withsparseread = getattr(r, '_withsparseread', False)
 
     def revinfo(rev):