talking to pre-4.1 servers or 4.1 and later servers where the old_passwords
option is enabled. "mysqladmin old-password" is unchanged. (Bug #7451)


client/mysqladmin.cc:
  Check old_passwords from server, and use that to determine
  which scramble function to use (except in the case of the
  old-password command, which always use the old scramble function).