Display company in status when main company has children

As soon as the main company has children, we must notice the user on which one
he is. The companies field contain only the children of the current company.

issue9403
review311921002

res.py

@@ -82,7 +82,7 @@ class User(metaclass=PoolMeta):
                 and len(list(filter(same_company, self.employees))) > 1):
             status += ' - %s' % self.employee.rec_name
         if self.company:
-            if len(self.companies) > 1:
+            if self.main_company.childs:
                 status += ' - %s' % self.company.rec_name
             status += ' [%s]' % self.company.currency.code
         return status