Similarly to #2426, put creation of remote statuses in a transaction, (#3233)

so that public timeline/caching would not encounter incomplete data

app/services/process_feed_service.rb

@@ -47,7 +47,11 @@ class ProcessFeedService < BaseService
         return
       end
 
+      status, just_created = nil
+
       Rails.logger.debug "Creating remote status #{id}"
+
+      ApplicationRecord.transaction do
         status, just_created = status_from_xml(@xml)
 
         return if status.nil?
@@ -66,6 +70,7 @@ class ProcessFeedService < BaseService
         end
 
         status.save!
+      end
 
       notify_about_mentions!(status) unless status.reblog?
       notify_about_reblog!(status) if status.reblog? && status.reblog.account.local?