--- a/mercurial/upgrade_utils/engine.py	Tue Jan 12 19:47:34 2021 +0100
+++ b/mercurial/upgrade_utils/engine.py	Wed Jan 13 12:50:47 2021 +0100
@@ -190,7 +190,7 @@
     # Perform a pass to collect metadata. This validates we can open all
     # source files and allows a unified progress bar to be displayed.
     for unencoded, encoded, size in alldatafiles:
-        if unencoded.endswith(b'.d'):
+        if not unencoded.endswith(b'.i'):
             continue
 
         rl = _revlogfrompath(srcrepo, unencoded)