Description:
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I'm getting this error on PHP 5.2.2 and haven't had a chance to upgrade to 5.2.4 yet, but I wanted to mention it anyway since it seems like it would be sort of a niche bug.

When iterating over XML using RecursiveIteratorIterator(SimpleXMLIterator(xml)), XPath expressions intended to retrieve a node's ancestors do not retrieve all of them.

In the below example, this means that only the immediate parent of the current node can be identified; in other test cases I've run, not even the parent was available.

Reproduce code:
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$xml = '<xml><fieldset1><field1/><field2/></fieldset1><fieldset2><options><option1/><option2/><option3/></options><field1/><field2/></fieldset2></xml>';

$sxe = new SimpleXMLIterator($xml);
$rit = new RecursiveIteratorIterator($sxe, RecursiveIteratorIterator::LEAVES_ONLY);
foreach ($rit as $child) {
	$path = '';
	$ancestry = $child->xpath('ancestor-or-self::*');
	foreach ($ancestry as $ancestor) {
		$path .= $ancestor->getName() . '/';
	}
	$path = substr($path, 0, strlen($path) - 1);
	echo count($ancestry) . ' steps: ' . $path . PHP_EOL;
}

Expected result:
----------------
3 steps: xml/fieldset1/field1
3 steps: xml/fieldset1/field2
1 steps: xml/fieldset2/options/option1
1 steps: xml/fieldset2/options/option2
1 steps: xml/fieldset2/options/option3
3 steps: xml/fieldset2/field1
3 steps: xml/fieldset2/field2

Actual result:
--------------
2 steps: fieldset1/field1
2 steps: fieldset1/field2
2 steps: options/option1
2 steps: options/option2
2 steps: options/option3
2 steps: fieldset2/field1
2 steps: fieldset2/field2