It's worth noting this has some impact on other internal classes that set get_iterator but don't implement Iterator or IteratorAggregate. There are at least a handful of those in ext/com_dotnet and ext/ffi. Not a big issue, just worth pointing out. I'm also not sure if this is a 8.4-only issue, so it should target either 8.3 or 8.5 (or master).

As it only reported to cause problems with hooks, I'd say 8.4 is the right target?

There are other classes with get_iterator that don't implement Traversable, so this will change behavior for 8.4 but not 8.3, which seems odd, if that interpretation of "is iterable" is wrong.