I've seen a case where one team developed a temporary hack to automate some process in their product, then allowed another team making a sibling product to use it to test a possible feature; soon after, the possible feature became an actual one, everyone seemingly forgot the API was a throwaway test. Over the years, as both products evolved, that feature got pretty flaky, and in one of many cross-team attempts at fixing it, someone from the original time finally pointed out that the whole thing is still relying on a temporary hack in the original product that was never intended to be productized...