diff -r d00177d08139 -r 19d4802cb304 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Mon May 03 12:29:41 2021 +0200
+++ b/mercurial/localrepo.py	Mon May 03 12:29:52 2021 +0200
@@ -737,6 +737,9 @@
     storevfs = store.vfs
     storevfs.options = resolvestorevfsoptions(ui, requirements, features)
 
+    if requirementsmod.REVLOGV2_REQUIREMENT in requirements:
+        features.add(repository.REPO_FEATURE_SIDE_DATA)
+
     # The cache vfs is used to manage cache files.
     cachevfs = vfsmod.vfs(cachepath, cacheaudited=True)
     cachevfs.createmode = store.createmode