For migrations of comments without a valid old_status, apply the 'published'

state.

CHANGES.txt

@@ -4,6 +4,10 @@ Changelog
 2.2.1 (unreleased)
 ------------------
 
+- For migrations of comments without a valid old_status, apply the 'published'
+  state.
+  [thet]
+
 - Re-apply eleddy's "Revert modification date since this is fixed in
   p.a.caching now." as her commit was lost later on due to some git magic.
   [thet]

plone/app/discussion/browser/migration.py

@@ -121,9 +121,10 @@ class View(BrowserView):
                         'action': None,
                         'actor': None,
                         'comment': 'Migrated workflow state',
-                        'review_state': old_status.get(
+                        'review_state': old_status and old_status.get(
                             'review_state',
-                            new_workflow.initial_state),
+                            new_workflow.initial_state)
+                            or 'published',
                         'time': DateTime()
                     }
                     workflow.setStatusOf('comment_review_workflow',