Description:
------------
I try to access a particular element of xml data with the
foreach($xml->name_of_element ....) syntax.

But I don't know if this element exists.

When the element don't exists, no problem the first time;
It don't goes inside the loop.

But If I call the same loop a second time, it goes inside the loop, as if the element exists.


Reproduce code:
---------------
 $string = "<data><typebal1>pim</typebal1><typebal2>poom</typebal2></data>";


 $xml = simplexml_load_string($string);

 foreach($xml->typebal3 as $bal) {
 	print "<br />I should not be here<br />";	
 }

 foreach($xml->typebal3 as $bal) {
 	print "<br />I should either not be here<br />";	
 }

 //this script renders "I should either not be here"

Expected result:
----------------
this script should not print anything

Actual result:
--------------
this script renders "I should either not be here"