Title: Fixed possible corruption of user datasets (contact, mail, rbn config)
Level: 1
Component: wato
Class: fix
Compatible: compat
State: unknown
Version: 1.2.7i3
Date: 1437639107

When moving user notification rules in an installation where a lot of users
are working with the GUI, it could happen that the file which stores contact,
mail and user rbn configuration (contacts.mk) could corrupt and lead to lost
attributes for all the users.
