Rudder

On Rudder 2.8, we introduced a new way to compute the allowed network (http://www.rudder-project.org/redmine/issues/4380)
However, for some reason, the merge 2.8 -> 2.9 did not include this modification !
Indeed, the code there https://github.com/Normation/rudder/pull/429/files does not appear in 2.9.

We need to reapply this modification, and understand why the merge failed