[libdazzle] tree: avoid returning dummy nodes

[Christian Hergert <chergert src gnome org>]

commit d8a42a7b9ba9feb4eb55b03d0eff283d9f658681
Author: Christian Hergert <chergert redhat com>
Date:   Tue Dec 5 18:13:12 2017 -0800

    tree: avoid returning dummy nodes

 src/tree/dzl-tree-node.c |    4 ++++
 src/tree/dzl-tree.c      |    1 +
 2 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/src/tree/dzl-tree-node.c b/src/tree/dzl-tree-node.c
index 04b0a4e..05b357e 100644
--- a/src/tree/dzl-tree-node.c
+++ b/src/tree/dzl-tree-node.c
@@ -1288,6 +1288,10 @@ dzl_tree_node_nth_child (DzlTreeNode *self,
           gtk_tree_model_get (model, &iter, 0, &node, -1);
           g_assert (DZL_IS_TREE_NODE (node));
 
+          /* Don't hand back a dummy node */
+          if (_dzl_tree_node_is_dummy (node))
+            return NULL;
+
           return g_steal_pointer (&node);
         }
     }
diff --git a/src/tree/dzl-tree.c b/src/tree/dzl-tree.c
index db3391b..35f890c 100644
--- a/src/tree/dzl-tree.c
+++ b/src/tree/dzl-tree.c
@@ -522,6 +522,7 @@ _dzl_tree_insert_sorted (DzlTree                *self,
 
   _dzl_tree_node_set_tree (child, self);
   _dzl_tree_node_set_parent (child, node);
+  _dzl_tree_node_set_needs_build (child, TRUE);
 
   g_object_ref_sink (child);