warning message at command line `sudo`

After a little Googling, I found out this message is related to Samba password syncing.

To fix it, run pam-auth-update and make sure SMB password synchronization is deselected (source). Use space to deselect it.

This should not be necessary when the bug is corrected in SAMBA (in fact, Ubuntu 14.10 is packed with samba 4.1.11 and does not have the same behavior).