Description:
------------
Functions dba_firstkey/nextkey ignore specified db handle and use last opened DBM database.

Reproduce code:
---------------
#!/usr/local/bin/php
<?
$db_one = dba_open("datadb_one","r","dbm");
$db_two = dba_open("datadb_two","r","dbm");      
 
if ($key = dba_firstkey($db_one) {
  do { 
    echo("$key\n");
  } while ($key = dba_nextkey($db_one));
}  
?> 


Expected result:
----------------
Keys from datadb_one

Actual result:
--------------
Keys from datadb_two (from last opened database).