I would prefer to keep this information in version control. A commit message with a thorough explanation of why the previous version failed and how the change r

I would prefer to keep this information in version control. A commit message with a thorough explanation of why the previous version failed and how the change resolves the problem would accomplish the same thing as a comment in the code, but it wouldn't clutter the correct version. And as others have said, you could add some unit tests to prevent others (or your future self) from creating a regression.