Fix playbooks such that they work with external inventory scripts. We really…

Fix playbooks such that they work with external inventory scripts.  We really want to find out why the 'all'
group isn't available, but group vars don't make sense for external inventory anyway.

lib/ansible/playbook.py

@@ -108,12 +108,13 @@ class PlayBook(object):
         if override_hosts is not None:
             if type(override_hosts) != list:
                 raise errors.AnsibleError("override hosts must be a list")
-            self.global_vars.update(ansible.inventory.Inventory(host_list).get_group_variables('all'))
-            self.inventory = ansible.inventory.Inventory(override_hosts)
+            if not self.inventory._is_script:
+                self.global_vars.update(ansible.inventory.Inventory(host_list).get_group_variables('all'))
 
         else:
             self.inventory = ansible.inventory.Inventory(host_list)
-            self.global_vars.update(ansible.inventory.Inventory(host_list).get_group_variables('all'))
+            if not self.inventory._is_script:
+                self.global_vars.update(ansible.inventory.Inventory(host_list).get_group_variables('all'))
 
         self.basedir          = os.path.dirname(playbook)
         self.playbook         = self._parse_playbook(playbook)