diff -r d86908050375 -r 96aa3a68d3b5 mercurial/revlogutils/rewrite.py
--- a/mercurial/revlogutils/rewrite.py	Thu Oct 21 11:21:21 2021 +0200
+++ b/mercurial/revlogutils/rewrite.py	Thu Oct 21 17:25:41 2021 +0200
@@ -589,7 +589,9 @@
     except error.CensoredNodeError:
         # We don't care about censored nodes as they never carry metadata
         return False
-    has_meta = raw_text.startswith(b'\x01\n')
+
+    # raw text can be a `memoryview`, which doesn't implement `startswith`
+    has_meta = bytes(raw_text[:2]) == b'\x01\n'
     if metadata_cache is not None:
         metadata_cache[filerev] = has_meta
     if has_meta: