diff --git a/mercurial/upgrade_utils/actions.py b/mercurial/upgrade_utils/actions.py
--- a/mercurial/upgrade_utils/actions.py
+++ b/mercurial/upgrade_utils/actions.py
@@ -33,6 +33,7 @@
     requirements.CHANGELOGV2_REQUIREMENT,
 }
 
+
 def preservedrequirements(repo):
     preserved = {
         requirements.SHARED_REQUIREMENT,