[libdazzle] listbox: properly clear head of cached rows

[Christian Hergert <chergert src gnome org>]

commit 1aed7b3b9d525609d132c45cb9390d0dcb444753
Author: Christian Hergert <chergert redhat com>
Date:   Tue Sep 5 01:33:26 2017 -0700

    listbox: properly clear head of cached rows
    
    When stealing the rows for disposal, we need to ensure we clear out the
    head of the queue as well.

 src/widgets/dzl-list-box.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/widgets/dzl-list-box.c b/src/widgets/dzl-list-box.c
index 228d121..8f20633 100644
--- a/src/widgets/dzl-list-box.c
+++ b/src/widgets/dzl-list-box.c
@@ -166,6 +166,8 @@ dzl_list_box_destroy (GtkWidget *widget)
   priv->recycle_max = 0;
 
   rows = priv->trashed_rows.head;
+
+  priv->trashed_rows.head = NULL;
   priv->trashed_rows.tail = NULL;
   priv->trashed_rows.length = 0;