[gtk+] rbtree: Add assertions to clarify usage

[Benjamin Otte <otte src gnome org>]

commit 6168a64713a9eb670db8e2e054e48c524553ea1b
Author: Benjamin Otte <otte redhat com>
Date:   Mon Nov 21 19:51:39 2011 +0100

    rbtree: Add assertions to clarify usage

 gtk/gtkrbtree.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkrbtree.c b/gtk/gtkrbtree.c
index 53faea2..279df20 100644
--- a/gtk/gtkrbtree.c
+++ b/gtk/gtkrbtree.c
@@ -472,6 +472,7 @@ _gtk_rbtree_insert_after (GtkRBTree *tree,
     }
   else
     {
+      g_assert (tree->root == tree->nil);
       tree->root = node;
       tmp_node = tree->parent_node;
       tmp_tree = tree->parent_tree;
@@ -558,6 +559,7 @@ _gtk_rbtree_insert_before (GtkRBTree *tree,
     }
   else
     {
+      g_assert (tree->root == tree->nil);
       tree->root = node;
       tmp_node = tree->parent_node;
       tmp_tree = tree->parent_tree;