Description:
------------
Newly with PHP 4.3.2, calls to ob_start with an empty handler (i.e. ob_start("")) seem to be optimized out and ignored.

This causes two problems :
- ob_start("") can be useful if you prefer to process the
  contents manually by using ob_get_contents() and then
  ob_end_clean()
- nesting of output buffers is broken, because the ob_end()
  call corresponding to ob_start("") is still taken (which
  can totally break the page if your ob_start("") is nested
  inside an ob_start("ob_gzhandler")...)


Reproduce code:
---------------
** This one doesn't work (second statement is eaten out) :

<?php
                                                                                                           
ob_start("ob_gzhandler");
ob_start("");
echo "first echo<p>";
ob_end_flush();
echo "second echo<p>";
ob_end_flush();
?>

** This one works (both statements are printed) :

<?php
                                                                                                           
function foo($x) { return $x; }
                                                                                                           
ob_start("ob_gzhandler");
ob_start("foo");
echo "first echo<p>";
ob_end_flush();
echo "second echo<p>";
ob_end_flush();
?>



Expected result:
----------------
Both programs should have the same result (i.e. print both statements on screen).


Actual result:
--------------
The program which calls ob_start with an empty handler fails to display the second statement. In the other program, we circumvent this bug by using a dummy handler, which causes it to work properly.