diff -r 4ba2a6ffcf24 -r 526d69eeea31 mercurial/upgrade.py
--- a/mercurial/upgrade.py	Tue May 12 11:39:50 2020 +0200
+++ b/mercurial/upgrade.py	Tue Apr 14 06:09:14 2020 +0200
@@ -78,6 +78,7 @@
         localrepo.SPARSEREVLOG_REQUIREMENT,
         localrepo.SIDEDATA_REQUIREMENT,
         localrepo.COPIESSDC_REQUIREMENT,
+        localrepo.NODEMAP_REQUIREMENT,
     }
     for name in compression.compengines:
         engine = compression.compengines[name]
@@ -105,6 +106,7 @@
         localrepo.SPARSEREVLOG_REQUIREMENT,
         localrepo.SIDEDATA_REQUIREMENT,
         localrepo.COPIESSDC_REQUIREMENT,
+        localrepo.NODEMAP_REQUIREMENT,
     }
     for name in compression.compengines:
         engine = compression.compengines[name]
@@ -132,6 +134,7 @@
         localrepo.SPARSEREVLOG_REQUIREMENT,
         localrepo.SIDEDATA_REQUIREMENT,
         localrepo.COPIESSDC_REQUIREMENT,
+        localrepo.NODEMAP_REQUIREMENT,
     }
     for name in compression.compengines:
         engine = compression.compengines[name]
@@ -990,7 +993,7 @@
     Function should return ``True`` if the file is to be copied.
     """
     # Skip revlogs.
-    if path.endswith((b'.i', b'.d')):
+    if path.endswith((b'.i', b'.d', b'.n', b'.nd')):
         return False
     # Skip transaction related files.
     if path.startswith(b'undo'):