diff -r 0ec94359eae8 -r 362d5a2ffd17 mercurial/mdiff.py
--- a/mercurial/mdiff.py	Thu Feb 02 17:30:50 2023 +0100
+++ b/mercurial/mdiff.py	Thu Feb 02 17:32:38 2023 +0100
@@ -213,7 +213,7 @@
     if (
         opts is None
         or not opts.xdiff
-        or not util.safehasattr(bdiff, b'xdiffblocks')
+        or not util.safehasattr(bdiff, 'xdiffblocks')
     ):
         return bdiff.blocks
     else: