Merge pull request '#203' (#204) from feature/203 into main

Reviewed-on: https://git.miteruzo.com/miteruzo/btrc-hub/pulls/204

backend/lib/tasks/migrate_wiki.rake

@@ -44,6 +44,7 @@ namespace :wiki do
         end
         line_ids = line_shas.map { |sha| line_id_by_sha.fetch(sha) }
 
+        rev = nil
         ActiveRecord::Base.transaction do
           wiki_page.lock!