Description:
------------
isset() and unset() on SimpleXML properties do not take the element namespace into account. isset() returns true if there is an element with that name in *any* namespace and unset() removes the property from *all* namespaces.

Test script:
---------------
<?php

$xml = new SimpleXMLElement('<root xmlns:ns="ns"><foo>bar</foo><ns:foo>ns:bar</ns:foo><ns:foo2>ns:bar2</ns:foo2></root>');
var_dump(isset($xml->foo2));
unset($xml->foo);
var_dump($xml->children('ns'));

Expected result:
----------------
bool(false)
object(SimpleXMLElement)#2 (2) {
  ["foo"]=>
  string(6) "ns:bar"
  ["foo2"]=>
  string(7) "ns:bar2"
}

Actual result:
--------------
bool(true)
object(SimpleXMLElement)#2 (1) {
  ["foo2"]=>
  string(7) "ns:bar2"
}