diff -r 5af4a0a73e4c -r 0fca63953810 mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py	Mon Nov 07 17:57:28 2022 -0500
+++ b/mercurial/revlogutils/deltas.py	Mon Nov 07 20:02:32 2022 -0500
@@ -1071,7 +1071,7 @@
                 snapshotdepth = len(revlog._deltachain(deltabase)[0])
         delta = None
         if revinfo.cachedelta:
-            cachebase, cachediff = revinfo.cachedelta
+            cachebase = revinfo.cachedelta[0]
             # check if the diff still apply
             currentbase = cachebase
             while (