- Migrate a question (with votes) to a site
- On the site that received the question, try merging the question with an existing one, choosing to remove the migrated question.
- You will get an error message.
For more information (and some comments by @waffles that might help), see this chat: http://chat.meta.stackoverflow.com/transcript/message/223820#223820
Credit for the awesome title goes to @random