one year of a bug
A year ago I wrote a script for managing reusable components in FrameMaker. It has being expensively used. Saying more, it's a core of a new workflow.
Recently users reported a bug. Their comments for components where not displaying.
After some exploration, I realized that comments never were used by the code. At the time of writing the script there were no comments and even no agreement on how to make comments, so I implemented a fallback behaviour (using the first paragraph of a component as the comment).
All the year the users were getting the fallback behavior, and it was right!