Rudder

We introduced a change in 3.1 that made the FQDN attribute in inventory mandatory. The reason for that was that the attribute we were relying upon in 3.0 and before (HOSTNAME ?) was sometime badly filled, and the value was not the real fqdn but only the hostname, which proved to lead to errors afterward.

However, in some cases the FQDN attribute may be empty due to bad behaviour of the perl command used by fusion inventory to find it.

So we have two cases to manage:

- correct the bug at fusion inventory level so that on the long run, we can effectivelly rely only on FQDN (maanged in parent ticket #7001)
- find a way to be able to have a Rudder 3.1 server with nodes on Rudder < 3.1 - so actually, use something else than FQDN when that attribute is empty, most likelly what we were using until 3.1 (even if it is sometime filled with a bad value, that will greatly reduce the total pourcentage of error compared to pre-3.1 versions) => this ticket.