Description:
------------
[Note: This bug is against PHP 5.1.6, but the bug interface only offers 5.1.5.]

The code below makes PHP segfault at the time that exit() is called. This happens with both CLI and Apache 2 (prefork).  I'm using MySQL 4.1.11.

If the return value of prepare() is not assigned to a variable, the script does not crash. Also it does not crash when omitting the exit() call.

Reproduce code:
---------------
<?php
class SomeClass {

    public function doSomething($id) {
        $dsn = "mysql:host=localhost;dbname=weblog";
        $db = new PDO($dsn, "weblog", "weblog");

        $stm = $db->prepare("UPDATE entry SET id = ?");

        exit();
    }
}

$obj = new SomeClass;
$obj->doSomething(1);


Expected result:
----------------
No crash.

Actual result:
--------------
#0  0x4011c927 in mysql_more_results () from /usr//lib/libmysqlclient.so.14
#1  0x08134329 in free_statement (stmt=0x84e351c) at /home/martin/src/php-5.1.6/ext/pdo/pdo_stmt.c:2200
#2  0x082a2349 in zend_objects_store_free_object_storage (objects=0x83f60dc) at /home/martin/src/php-5.1.6/Zend/zend_objects_API.c:86
#3  0x0828062f in shutdown_executor () at /home/martin/src/php-5.1.6/Zend/zend_execute_API.c:281
#4  0x0828b074 in zend_deactivate () at /home/martin/src/php-5.1.6/Zend/zend.c:854
#5  0x082513b6 in php_request_shutdown (dummy=0x0) at /home/martin/src/php-5.1.6/main/main.c:1292
#6  0x082f0cc0 in main (argc=3, argv=0xbffffb84) at /home/martin/src/php-5.1.6/sapi/cli/php_cli.c:1246