diff -r bb6902cbbe23 -r 164bbf674bb6 mercurial/upgrade.py
--- a/mercurial/upgrade.py	Fri Sep 27 21:14:03 2019 +0200
+++ b/mercurial/upgrade.py	Fri Sep 27 21:14:23 2019 +0200
@@ -561,7 +561,7 @@
         pass # create all the directories
 
     util.copyfile(oldindex, newindex)
-    if oldrl.opener.exists(olddata):
+    if oldrl.opener.exists(oldrl.datafile):
         util.copyfile(olddata, newdata)
 
     if not (unencodedname.endswith('00changelog.i')