Description:
------------
Having upgraded from 5.4.0 to 5.4.5, I now get the zlib output compression handler 
as part of ob_list_handlers() randomly which generates issues with ob_start().

zlib.output_compression is set to off.

'./configure' '--sysconfdir=/etc' '--with-config-file-path=/etc' '--with-config-
file-scan-dir=/etc/php.d' '--with-apxs2=/usr/sbin/apxs' '--with-openssl' '--with-
gd' '--with-curl=/usr/src/curl-7.21.7/include' '--with-zlib' '--enable-calendar' 
'--enable-mbstring' '--enable-zip' '--enable-sockets' '--with-mcrypt' '--with-
mysql=mysqlnd' '--with-mysqli=mysqlnd' '--with-pdo-mysql=mysqlnd' '--with-
kerberos' '--enable-ftp' '--disable-posix' '--enable-bcmath' '--enable-gd-native-
ttf' '--with-freetype-dir' '--with-jpeg-dir=/usr/local' '--with-png-
dir=/usr/local' '--with-xsl=/usr/local/lib' '--enable-exif'

Test script:
---------------
<?php
//using output_buffering=On
print_r(ob_list_handlers());
ob_end_flush();

ob_start("ob_gzhandler");
print_r(ob_list_handlers());
ob_end_flush();

// anonymous functions
ob_start(create_function('$string', 'return $string;'));
print_r(ob_list_handlers());
ob_end_flush();

Expected result:
----------------
Array
(
    [0] => default output handler
)

Array
(
    [0] => ob_gzhandler
)

Array
(
    [0] => default output handler
)

Actual result:
--------------
First execution (in browser)
Array
(
    [0] => default output handler
)
Array
(
    [0] => ob_gzhandler
)
Array
(
    [0] => 
)

Second execution (in browser)
Firefox 16.1a
Array
(
    [0] => default output handler
    [1] => zlib output compression
)


Chrome 2.0.1132.57
Array
(
    [0] => default output handler
    [1] => zlib output compression
)
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C°Šü¤øô*˜¸&HùÓàDArray
(
    [0] => default output handler
    [1] => 
)