Title: if64: Grouping of interfaces resulted in an exception
Level: 1
Component: checks
Class: fix
Compatible: compat
State: unknown
Version: 1.2.8b1
Date: 1446816126

The grouping of interfaces which are checked with the if64 check
was broken. This has been fixed now.

Grouping of interfaces across cluster nodes is undefined behaviour.
Added an error message to inform the users in case they configured
grouping for clustered interfaces.
