group refcount checking was inconsistent.

- if a group has one or more objects in it, it gets a refcount of 1 on load (unchanged from before)
- dupli-groups, and materials no longer add/remove a reference.
- now groups are only freed when they contain no objects or when manually unlinked.	

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/editors/object/object_edit.c b/source/blender/editors/object/object_edit.c
index d3226b1adf4..5fe09f0083e 100644
--- a/source/blender/editors/object/object_edit.c
+++ b/source/blender/editors/object/object_edit.c
@@ -1408,7 +1408,7 @@ void copy_attr(Scene *scene, View3D *v3d, short event)
 
 					base->object->dup_group= ob->dup_group;
 					if(ob->dup_group)
-						id_us_plus((ID *)ob->dup_group);
+						id_lib_extern(&ob->dup_group->id);
 				}
 				else if(event==7) {	/* mass */
 					base->object->mass= ob->mass;