diff -r b8d0761a85c7 -r 0147a4730420 mercurial/upgrade.py
--- a/mercurial/upgrade.py	Wed Feb 21 16:47:39 2018 -0800
+++ b/mercurial/upgrade.py	Thu Feb 22 20:04:42 2018 -0500
@@ -46,7 +46,6 @@
     return {
         # The upgrade code does not yet support these experimental features.
         # This is an artificial limitation.
-        'manifestv2',
         'treemanifest',
         # This was a precursor to generaldelta and was never enabled by default.
         # It should (hopefully) not exist in the wild.