Description:
------------
Updating node value result inserting selected node.
PHP should update value, NOT inserting selected node.

This bug is located at ext/simplexml.c

static int sxe_prop_dim_write(zval *object, zval *member, zval *value, zend_bool 
elements, zend_bool attribs, xmlNodePtr *pnewnode TSRMLS_DC)

It seems the logic is broken for this case.


Test script:
---------------
<?php
$string = <<<XML
<?xml version="1.0" ?> 
 <root>
    <node>
    value
    </node>
 </root>
XML;

$xml = simplexml_load_string($string);

$xml->root->node = "NEW VALUE";

print $xml->asXML();


Expected result:
----------------
<?xml version="1.0"?>
<root>
    <node>
    value
    </node>
 <root><node>NEW VALUE</node></root></root>


Actual result:
--------------
<?xml version="1.0"?>
<root>
    <node>
    NEW VALUE
    </node>
</root>