samba - May 1998 - problems with %o in passwd chat

I have a problem with the use of the %o macro in my passwd chat.
   passwd chat = *Enter\slogin(NIS)\spassword:* %o\n *New\spassword:*
"%n\n" *new\spassword:* "%n\n"

It behaves as if %o isn't replaced by the old password (no problem with
%n)

My log.smb contains:

   Doing SamOEMChangePassword
   ...
   Password change for user: user1
   Passwords: old= new=new123
   Dochild for user user1 (uid=0,gid=0)
   talktochild: chatbuf=[*Enter login(NIS) password:*]
responsebuf=[Enter login(NIS) password: ]
   talktochild: sendbuf=[
   ]
   talktochild: chatbuf=[*New password:*] responsebuf=[
   Sorry: wrong passwd

I found this in ipc.c :

  1671  static BOOL api_SamOEMChangePassword
  ...
  1721   if(lp_unix_password_sync())
  1722      ret = chgpasswd(user,"", new_passwd, True);

It looks like the old password isn't sent to the chgpasswd function.
Is it the intended effect or does I misunderstand something ?

Thanks in advance,

   Thomas.

I'm using the latest CVS main branch under Solaris 2.5 and Samba as a PDC.