Description:
------------
In php_mysql.c:

/* {{{ php_mysql_set_default_link
 */
static void php_mysql_set_default_link(int id TSRMLS_DC)
{
    MySG(default_link) = id;
    zend_list_addref(id);
}
/* }}} */

if MySG(default_link) is already set (!= -1), the above code needs to deref it before setting the default_link.  Otherwise a mysql_close down the road on the original default_link will not actually close the connection (it has too many references now).

Reproduce code:
---------------
A possible patch:

--- php-4.3.6.orig/ext/mysql/php_mysql.c        2004-06-03 16:08:29.124642476 -0500
+++ php-4.3.6/ext/mysql/php_mysql.c     2004-06-03 16:13:21.192405843 -0500
@@ -259,6 +259,9 @@
  */
 static void php_mysql_set_default_link(int id TSRMLS_DC)
 {
+       if (MySG(default_link)!=-1) {
+               zend_list_delete(MySG(default_link));
+       }
        MySG(default_link) = id;
        zend_list_addref(id);
 }