I definitely support adding a close() method, and a ResourceWarning if the iterator is not exhausted when it is deallocated. Adding context manager support is probably worthwhile as well, though there is one disadvantage: it would be hard to implement scandir() as a plain generator, because generators don’t support the context manager protocol. But C Python’s implementation is in C, and even in native Python you could implement it as a custom iterator class.

I suggest using this issue for adding the new API(s), presumably to 3.6 only, and Issue 26111 for adding a warning to the existing 3.5 documentation.