Description:
------------
The manual states that ini_set() "returns the old value on success, FALSE on failure".

When the initial value of a configuration option is an empty string ini_set() will give a misleading result as shown on the test case below. 

This bug is related to 41922.

The ini_set() code which causes the problem is:

old_value = zend_ini_string(Z_STRVAL_PP(varname), Z_STRLEN_PP(varname)+1, 0);

/* copy to return here, because alter might free it! */
if (old_value) {
        RETVAL_STRING(old_value, 1);
} else {
        RETVAL_FALSE;
}

So if response is NULL  we set a return code of FALSE.





Reproduce code:
---------------
--TEST--
Test to make sure that ini_set returns old value on success, false on failure
--FILE--
<?php
var_dump(ini_get("error_log"));
var_dump(ini_set("error_log","/tmp/log"));
var_dump(ini_get("error_log"));
?>
--EXPECT--
string(0) ""
string(0) ""
string(8) "/tmp/log"


Expected result:
----------------
See above

Actual result:
--------------
bool(false) <-- see bug 41922
bool(false) <-- implies ini_set() failure, it actually succeeds.
string(8) "/tmp/log"