Do not rely on activity arriving exactly once after delete arrived (#4754)

app/lib/activitypub/activity.rb

@@ -97,14 +97,7 @@ class ActivityPub::Activity
   end
 
   def delete_arrived_first?(uri)
-    key = "delete_upon_arrival:#{@account.id}:#{uri}"
-
-    if redis.exists(key)
-      redis.del(key)
-      true
-    else
-      false
-    end
+    redis.exists("delete_upon_arrival:#{@account.id}:#{uri}")
   end
 
   def delete_later!(uri)

app/lib/activitypub/activity/delete.rb

@@ -5,13 +5,13 @@ class ActivityPub::Activity::Delete < ActivityPub::Activity
     status   = Status.find_by(uri: object_uri, account: @account)
     status ||= Status.find_by(uri: @object['_:atomUri'], account: @account) if @object.is_a?(Hash) && @object['_:atomUri'].present?
 
-    if status.nil?
     delete_later!(object_uri)
-    else
+
+    return if status.nil?
+
     forward_for_reblogs(status)
     delete_now!(status)
   end
-  end
 
   private