Description:
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When extending an ArrayIterator, the get_iterator handler is overridden with spl_array_get_iterator **during object construction**: https://github.com/php/php-src/blob/8ee78441f87d59f22c2e6865a31e87f5076500da/ext/spl/spl_array.c#L211

This is incompatible with preloading, as the class is immutable at this point.

We can't simply remove the assignment, because this would break by-ref iteration of objects extending ArrayIterator.

Another way to handle this would be to inherit get_iterator in the interface_gets_implemented handlers for Iterator/IteratorAggregate. Unfortunately this also doesn't work, because some code (e.g. RecursiveIteratorIterator) assumes that the user get_iterator handler will be used if the class is inherited (it does not deal with overridden iterator methods).

Test script:
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<?php
class Foo extends ArrayIterator {}
new Foo([]);