Description:
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When we do a foreach on an arrayObject, and we want to unset some item from the loop a NOTICE is thrown.

Don't know if this is the intended behaviour but in case of doubt I prefer to submit.

Reproduce code:
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$coll = new ArrayObject();
$coll->append(new stdClass());
foreach ($coll as $index => $item) {
	$coll->offsetUnset($index);
}

Expected result:
----------------
nothing

Actual result:
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Notice: main() [function.main]: ArrayIterator::next(): Array was modified outside object and internal position is no longer valid in index.php on line 7