--- a/mercurial/revlog.py	Wed Jan 26 15:32:18 2022 -0800
+++ b/mercurial/revlog.py	Wed Feb 02 17:24:05 2022 +0100
@@ -1971,7 +1971,7 @@
             raise error.RevlogError(
                 _(b"%s not found in the transaction") % self._indexfile
             )
-        trindex = 0
+        trindex = None
         tr.add(self._datafile, 0)
 
         existing_handles = False
@@ -1994,10 +1994,17 @@
             with self._indexfp() as read_ifh:
                 for r in self:
                     new_dfh.write(self._getsegmentforrevs(r, r, df=read_ifh)[1])
-                    if troffset <= self.start(r) + r * self.index.entry_size:
+                    if (
+                        trindex is None
+                        and troffset
+                        <= self.start(r) + r * self.index.entry_size
+                    ):
                         trindex = r
                 new_dfh.flush()
 
+            if trindex is None:
+                trindex = 0
+
             with self.__index_new_fp() as fp:
                 self._format_flags &= ~FLAG_INLINE_DATA
                 self._inline = False